The bottom line for patrol (TL;DR)
- The verdict: The Demko AD20.5 is a “King of the Mountain” contender for duty carry fixed-blade strength in a slim folder.
- Top feature: The Shark-Lock provides the quickest one-handed deployment and retraction on the market.
- Durability: Survived months of prying and wire cutting without developing blade play.
- Maintenance: S35VN steel is tough and easy to sharpen with average skills.
I tested a Demko Knives AD20.5 in S35VN with Digi Camo G10 scales. This is a folding knife with a 3” blade and a unique locking system. I didn’t just “unbox” this; I beat it up for several months before I completed this review. In that time, it has displaced several others in my EDC kit.
Configurations and build
The Demko AD20.5 comes in several configurations, including a Sharksfoot style, which has a 2.875" cutting surface and a back that curves toward the blade in a style similar to a sheepsfoot blade. Both blade styles have a generous amount of jimping, featuring both a thumb stud and a thumb slot.
I measured the blade thickness at .130", which is a lot of “meat” on a folder. Considering the AD20.5 is built with a reinforced steel liner, it remains surprisingly thin when clipped to the pocket. It features six pins altogether, plus a large pivot pin with a T10 head. In flex tests, the blade remained centered in the liner and unaffected by stress. The pin design also allowed for easy cleaning and maintenance.
The magic of the Shark-Lock
The AD20.5 series uses the Shark-Lock, a fin-shaped protrusion on the spine of the knife. When the blade is deployed, the fin acts as a ramp that perfectly positions the thumb for full leverage on the tip. The user pulls back on this fin to fold the knife.
The spring-loaded mechanism fits into a machined recess in the tang over its pivot point. The tang and locking engagement area is much larger than most knives I have tested; this is a lot of steel-on-steel locking. This design creates three mechanical situations:
- Fixed-blade strength: The knife blade is pinned under this mechanism in a manner that makes it wobble-free and as strong as a fixed blade.
- Precision tension: The opening geometry is so precise that it keeps the closed blade under tension, yet it swings open effortlessly without any spring assist.
- Safety and speed: The blade is deployable and retractable one-handed, making it one of the most powerful and safest mechanisms available.
“I break things for a living”
If you served in the military, you probably had a service member like me. Every unit has one. When I lined up to turn in my equipment, my stuff was neatly packaged, but half of it was broken. I break things.
As a police officer, I have to apologize to the taxpayers in my city: I broke equipment there, too. After a while, I thought I should put my rough handling and clumsiness to good use. I embarked on my career as a product reviewer. More than 25 years later, I still break things for a living.
The Demko AD20.5 survived these tests completely intact. Considering the steel and build, I didn’t expect the knife to fail (it didn’t), but I also didn’t expect this to be the most usable and ergonomic knife in my recent experience.
S35VN performance and sharpening
S35VN is a steel usually chosen for its toughness (resistance to chipping) and ease of maintenance. The quality of this steel has more to do with its treatment than its makeup. It really is a steel that can do most tasks well without being deficient in any qualities. I like it because it is easy to keep a razor-sharp edge on it. It’s perfect for the AD20.5.
I did the usual rope cutting test — cutting a section of hemp braid 100 times — then inspected the edge. However, the real testing is when I use the blade for everything for months:
- The kitchen test: I started fixing my meals with it. My wife might be wondering how I sliced meat and tomatoes and never took a kitchen knife from the butcher block.
- The utility test: I cut cord and even wire. I pried bullets out of ballistic gelatin, opened packages and repaired things with it.
- The combat potential: I am a marginal user of knives for defense, but this knife gives the quickest and most reliable deployment of any I’m using now. I showed this around, and everyone thinks this is a great knife to incorporate into a martial arts training system. (Perhaps they could make a trainer version!)
Maintenance and value
The AD20.5 favors a 1500 or finer stone — I use a man-made abrasive stone — to draw out the fineness of the edge. My sharpening skills are only average, but a fine cutting edge was not a problem with this steel.
Configurations and pricing
If I had not picked the Digi Camo G10, I would have picked the black G10 with texturing (MSRP $250). These scales are a bit more aggressive. This model varies from the gray Grivory (MSRP $149) to the model tested (MSRP $250). For a premium knife, these are great prices. Demko Knives has recently released the Nano Shark, a similar design with a 2.125 blade. The Shark-Lock design has become quite iconic, and there are aftermarket scales popping up all over the place, which should tell you something about the end user friendly design. Actually, you don’t need to go to aftermarket sources. Demko Knives sells scales, springs and stainless standoffs online.
Final thoughts
I think this knife is approaching “King of the Mountain” status in production knives. Demko Knives has a lot of things going on right now, including U.S.-made Magnacut models and premium versions of their production knives, which can be found on the Arizona Custom Knives page. This is the brand to watch for 2026. View the full line at Demko Knives.
