Opinel Slim Series Fillet Knife Review
Opinel knives have been around for a while. Originally developed by Joseph Opinel in Savoie, France in 1890, they were originally intended to be simple working man’s knives. In a way, they still are. The Opinel knives of today are unfussy, affordable, and have changed little since the 19th century.
I recently picked up an Opinel No.10 Slim Series knife. It’s very similar to the original Opinel, but with some modifications that make it well-suited as a fillet knife. My old Rapala 4″ Fish’n Fillet Knife, after 20-plus years of faithful service, was beginning to show its age, so that’s exactly what I needed.

Opinel Slim Series: First Impressions
Opinel’s knives have never been about aesthetics, though there is something elegant about their simplicity. That said, they’re known for their basic, unadorned design, with simple collar locks and unfinished beech wood handles.
I have no problem with any of that, but I was happy to see that the Opinel Slim Series knives are a little more artfully designed than their forebears. While all the basic elements of an Opinel are there, both the blade and the handle have an elongated, gracefully curved shape. It fits my hand beautifully, and it’s light as a feather.
It’s simply a beautiful knife. Typical of Opinels, you can get these in various sizes, with numbers representing the length of the blade in centimeters. You can also get a few different handle wood options.

Measurements & Specs
The blade of the Opinel Slim Series No.10 measures—you guessed it—10 cm, or just a hair under 4 inches. Its full open length is about 8.8 inches, and it’s about 4.9 inches closed. The blade is made of Sandvik 12C27 Stainless Steel, and the handle (mine, anyway) is padauk wood. Beech and olive wood handles are also available.
It weighs about 1.4 ounces, which might sound impossibly light if you’ve never held an Opinel knife. But if you have, then you know these things are about as close as a knife gets to being weightless. They’re often considered to be good hiking knives for that reason.

Blade Shape & Steel
Typical of a fillet knife, the Opinel Slim Series has a blade that is long, narrow and thin. It’s designed to cut through and around bone, so it needs to be sharp and flexible. It’s both, easily passing a paper test right out of the box and continuing to do so after I’ve cleaned a few fish with it.
In place of the clip point blade you’ll find on a classic Opinel, the Slim Series has a trailing point blade; the spine is straight along most of its length, but arcs gently upward at the tip. Again, it’s well-designed for its intended purpose. The blade comes to an exceptionally fine point, which is good for piercing.
Sandvik 12c27 is not a high-end steel by any means. It’s pretty cheap stuff, which isn’t too shocking when you consider how affordable Opinel knives are. That being said, it has some good qualities.
It’s a very old steel alloy that contains a high amount of chromium (around 14%), making it exceptionally corrosion-resistant. It has good wear-resistance too, so it keeps an edge nicely. It’s also reasonably easy to sharpen compared to many other high-chromium stainless steels. Originating in Sweden, Sandvik 12c27 is really quite ideal for a filet knife. It’s also commonly used to make razor blades.

Locking & Deployment
The Opinel Slim Series has a collar lock, also known as a ring lock, which is one of those “it is what it is” features. Sure, there are better knife locks in the world, but the collar lock is essentially Opinel’s calling card at this point. It would be weird if it didn’t have one, and you pretty much know what you’re getting.
The lock can be slid back and forth between “locked” and “unlocked” one-handed with your thumb, but the blade cannot be deployed one-handed. It’s an old-school friction folder, which predates the invention of the slipjoint, so you’ll need to grasp the spine of the blade and pull it all the way out and around. Rotating the collar will lock the blade in either the open or closed position. It’s charmingly old-fashioned, though definitely not a fidget knife.
For me, it’s also not really a pocket knife, because the lock, when in the closed position, isn’t quite tight enough to keep the very tip of the blade from peeking out of its channel within the handle. My fillet knife lives in my tackle box, so that isn’t a huge issue. But the lackluster lock really creates the possibility of cutting yourself when reaching into your pocket for the knife.

Handle & Grip
The handle of the Opinel Slim Series No.10 is thoroughly comfortable. It has a very ergonomic contour, and the blade channel is unnoticeable against my palm. It’s quite nimble as well, making finely detailed tasks (i.e. filleting fish) easy and comfortable. Although it has no grip texture to speak of, the natural wood does a nice job holding tight in my hand, even in wet conditions.
Speaking of which, the padauk wood used to make the handle has excellent water resistance, at least by wood standards, so it’s less inclined to expand or crack with prolonged and repeated water exposure. It’s beautiful wood too, with a warm reddish color and handsome grain. Of course, wood is still wood, so it’s by no means waterproof. Dry it after each use, and oil it periodically to keep it in good condition.

Final Thoughts on the Opinel Slim Series
I bought this knife with a specific purpose in mind, and I really like it for that purpose. Most fillet knives are fixed-blades, and this is one of the best folding fillet knives I’ve seen. Everything about it, from the shape and sharpness of the blade to the types of steel and wood used, make it an ideal fishing knife.
Like all Opinels, the Slim Series knives are almost jarringly old-fashioned if you’re not used to them. There are a lot of folks who absolutely adore Opinel knives, and there are also plenty of people who hate them.
I tend to fall somewhere between those two camps. This isn’t a knife I would reach for on a day-to-day basis. It’s not at all heavy-duty (although it is quite a bit more sturdy than it looks in pictures) and I wouldn’t want to have to rely on it as my sole blade. But it performs beautifully when it comes to skinning, gutting, filleting and deboning fish, as well as other food prep.
For what it’s worth, the Opinel Slim Series No.10 is just the right size for cleaning fish like panfish, trout and small bass. For larger fish, Opinel makes these knives all the way up to No.15.
The Best-Selling Opinel Knives On Amazon Right Now:
- This essential tool is unchanged since 1890 and is a must have for outdoorsmen and handymen alike
- The Stainless Virobloc safety ring has two sections, one fixed and one sliding for secure locking
- Opinel’s stainless steel blades are made of Sandvik 12C27 modified stainless steel
- Handle is made from hard, durable Beechwood from France
- Opinel products are guaranteed under normal use and exchanged in case of manufacturing defects
- This essential tool is unchanged since 1890 and is a must have for outdoorsmen and handymen alike
- The Stainless Virobloc safety ring has two sections, one fixed and one sliding for secure locking
- Opinel’s carbon steel is extremely hard, thereby guaranteeing excellent cutting quality
- Handle is made from hard, durable Beechwood from France
- Opinel products are guaranteed under normal use and exchanged in case of manufacturing defects
- FLAGSHIP SIZE: The Number 8 is the most sold and versatile size in the ever-growing line of Opinel folding pocket knives, earning its reputation as an everyday carry staple. 3.35” blade (8.5cm), open length 7.5” (19.5cm).
- PATENTED VIROBLOC: A hallmark of Opinel everyday carry knives since it’s invention in 1955, the Virobloc ring offers a unique, thoughtful, and easy to use safety mechanism for locking the blade during use, during transport, and during storage.
- INOX BLADE: We use Sandvik 12C27 Modified Stainless Steel. It is anti-corrosive thanks to the addition of chrome and requires no special maintenance. Carbon content of at least 0.40% provides an excellent cutting edge and is easily sharpened.
- THE CROWNED HAND: In 1565 King Charles IX commanded every knife maker to stamp an emblem on their products to guarantee their origin and quality. In 1909 in order to honor this tradition Joseph Opinel chose the Crowned Hand as his emblem.
- AN ICON OF FRENCH CULTURE: Produced in the heart of the French Alps since 1890, Opinel knives draw simplicity and durability from their mountain roots. Opinel kitchen knives have been adopted worldwide and recognized as a design icon.
- DITCH THE DISPOSABLE: The Picnic+ cutlery set is a smart and durable accessory for on-the-go meals and camp cooking. Part of our Nomad Cooking Collection, you can ditch the disposable cutlery
- FLAGSHIP SIZE: The Number 8 is the most sold and versatile size in the ever-growing line of Opinel folding pocket knives, earning its reputation as an everyday carry staple. 3. 35inch blade (8. 5cm), open length 7. 5 inches (19. 5cm)
- MINIMALIST AL FRESCO TOOL: Perfect for hiking, weekend picnics, or just everyday lunches, the Picnic+ set utilizes the Virobloc safety ring on our No.08 folding knife to hold the fork and/or spoon insert in place
- MEALS ANYWHERE: Specifically designed to be lightweight and versatile, the Nomad collection is made up of a range of products that will make eating outdoors easy!
- COMPATIBILITY: Fork and spoon inserts compatible with all wooden handled No.08 folding knives equipped with the Virobloc safety ring. Picnic+ inserts are NOT compatible with No.08 Slim knives, No.08 Gardening knife and No.08 Mushroom knife
- WONDROUS WALNUT: This French wood is yellow brown or grey brown, and presents dark veins and overall color to contrast the lustrous stainless steel blade of this folding pocket knife. A refined take on the iconic Opinel.
- INOX BLADE: We use Sandvik 12C27 modified stainless steel. It is anti-corrosive thanks to the addition of chrome and requires no special maintenance. Carbon content of at least 0.40% provides an excellent cutting edge and is easily sharpened.
- THE CROWNED HAND: In 1565 King Charles IX commanded every knife maker to stamp an emblem on their products to guarantee their origin and quality. In 1909 in order to honor this tradition Joseph Opinel chose the Crowned Hand as his emblem
- PATENTED VIROBLOC: A hallmark of Opinel everyday carry knives since it’s invention in 1955, the Virobloc ring offers a unique, thoughtful, and easy to use safety mechanism for locking the blade during use, during transport, and during storage
- FRENCH HERITAGE: For over 130 years Opinel has been crafting knives and tools in the heart of the French Alps. Much like Joseph Opinel did from his workshop in 1890, today we still manufacture Opinel products from our factory in Chambery, France.
- PRACTICAL PARING ADDITION TO YOUR KITCHEN LINEUP: Essential Paring Knife Sets by Opinel are practical, useful tools fit for a wide range of tasks – from prep work to dressing up your table for a dinner party and everything in between
- PARING KNIFE: A must-have in your kitchen, a good paring knife is an essential tool for any chef. Use it to peel garlic, prune garnishes, mince small herbs, or trim fat from large cuts of meat, a paring knife is truly a do-it-all knife
- HIGH CARBON STAINLESS STEEL: Renowned by many, the 12C27 Swedish Stainless Steel is one of the highest quality steels in the world. Good edge retention, simple maintenance, and high resistance to corrosion make 12C27 a great choice for high use kitchen knives
- STABILIZED BEECHWOOD HANDLES: Sustainably harvested beechwood handles are varnished for extra protection against moisture, dirt, and wear over time.
- AN ICON OF FRENCH CULTURE: Produced in the heart of the French Alps since 1890, Opinel knives draw simplicity and durability from their mountain roots. Opinel kitchen knives have been adopted worldwide and recognized as a design icon
- Pick, remove dust, and clean your mushrooms all with one knife
- The Stainless Virobloc safety ring has two sections, one fixed and one sliding for secure locking
- Opinel’s stainless steel blades are made of Sandvik 12C27 modified stainless steel
- Handle is made from hard, durable Beechwood from France
- Opinel products are guaranteed under normal use and exchanged in case of manufacturing defects
- This essential tool is unchanged since 1890 and is a must have for outdoorsmen and handymen alike
- The Stainless Virobloc safety ring has two sections, one fixed and one sliding for secure locking
- Opinel’s stainless steel blades are made of Sandvik 12C27 modified stainless steel
- Handle is made from hard, durable Beechwood from France
- Opinel products are guaranteed under normal use and exchanged in case of manufacturing defects
- A FISHERMAN’S DREAM KNIFE: Specifically designed for filleting fish, these thin, flexible yet robust blades are ready for your next catch – Easy maintenance European stainless steel and naturally water resistant wooden handles
- UPDATED BLADE SHAPE: Updated for 2024, the Effile lineup now features a more slim blade profile with a straight back shape, in addition to a new size 15 available in all wood handle options
- SUSTAINABLY HARVESTED WOOD HANDLES: Choose between deep reds and browns of Padouk, brighter, softer Beech, or the fine veins of Olivewood, all harvested via sustainable methods from European forests
- MADE IN FRANCE: Little has changed since 1890. Rooted in history and a commitment to craftsmanship, the Opinel family still makes their knives in the Savoie region of France
- FINE DETAILS: Olive wood and Padouk wood models have mirror finished blades, No. 08 – 3.5” blade, 7.10” overall. No. 10 – 4” blade, 9.05” overall. No. 12 – 4.9” blade, 11” overall. No. 15 – 5.9” blade, 13” overall
- DITCH THE DISPOSABLE: The Picnic+ cutlery inserts are smart and durable accessories for on-the-go meals and camp cooking. Part of our Nomad Cooking Collection, you can ditch the disposable cutlery and replace it with our Picnic+ set
- MINIMALIST AL FRESCO TOOL: Perfect for hiking, weekend picnics, or just everyday lunches, the Picnic+ set utilizes the Virobloc safety ring on our No.08 folding knife to hold the fork and/or spoon insert in place
- MEALS ANYWHERE: Specifically designed to be lightweight and versatile, the Nomad collection is made up of a range of products that will make eating outdoors easy!
- COMPATIBILITY: Fork and spoon inserts compatible with all wooden handled No.08 folding knives equipped with the Virobloc safety ring. Picnic+ inserts are NOT compatible with No.08 Slim knives, No.08 Gardening knife and No.08 Mushroom knife

Blair Witkowski is an avid watch nut, loves pocket knives and flashlights, and when he is not trying to be a good dad to his nine kids, you will find him running or posting pics on Instagram. Besides writing articles for Tech Writer EDC he is also the founder of Lowcountry Style & Living. In addition to writing, he is focused on improving his client’s websites for his other passion, Search Engine Optimization. His wife Jennifer and he live in coastal South Carolina.