A knife’s utility isn’t defined by its blade alone—how it opens and locks can greatly influence performance, safety, and ease of use. In this guide, we’ll explore the most common knife mechanisms, explain how each works, and highlight their key features. By understanding the differences between slip-joint, flipper, AXIS® lock, AXIS® assisted, Auto AXIS®, and out-the-front systems, you’ll be better equipped to choose a knife that fits your style, whether for everyday carry, outdoor adventures, or tactical use. Along the way, we’ll show examples of knives that feature each mechanism so you can see them in action.
Slip-Joint Mechanism – Classic Folding Design
The first folding knives appeared in the Roman Empire around 600 BCE. Friction folders followed, held open by an extended blade tang in the user's grip. By the mid-1600s, the slip-joint emerged, using a backspring in the handle to apply tension against the blade tang, snapping it into open or closed positions with noticeable stops. Over time, this mechanism has evolved into refined, practical tools that balance craftsmanship with everyday functionality.
Photo: Dave Svarte/@dave_svarte
A modern example of this mechanism is the Successor™, which pairs classic folding functionality with a clean, minimalist design. The slip-joint allows smooth open-close operation with a solid half-stop, offering precision and control for daily carry. Its thoughtful design makes it easy to handle, reliable in everyday tasks, and versatile enough for both casual and refined use.
Best for: Everyday carry enthusiasts who value simplicity, craftsmanship, and a classic folding experience.
Photo: Dave Svarte/@dave_svarte
Lockback Mechanism – Classic and Secure
The Lockback is a modification of the slipjoint concept that incorporates a locking function to prevent the knife from closing until the user depresses the backspring to disengage the lock. Benchmade examples include the discontinued 15051-2 Big Summit Lake and the 15021-2 Small Summit Lake.
Best for: Users who want a simple, reliable lock with traditional appeal.
Liner Lock – Proven and Refined
The Liner Lock’s lineage dates back to the 19th century, with the first patent awarded in the early 1900s. Custom knifemaker Michael Walker refined the design in 1980, using a detent ball set into a leaf-spring cutout in the liner, called a lock bar, to hold the blade closed. When the blade is opened, the lock bar moves inward behind the blade tang. The liner lock bar engages with the back of the tang and must be manually pushed back toward the handle to disengage. Walker holds the trademark “Linerlock,” which is the standard for all modern liner locks. Past Benchmade models include the 601 Tengu by Jared Oeser, the Mel Pardue 850, and the 800 AFCK.
Best for: Users who want a reliable, widely-adopted, and intuitive locking mechanism.
RIL (Reeve Integral Lock)/Frame Lock – Strong and Reliable
The Reeve Integral Lock, also known as a Frame Lock, uses the same concept as a liner lock but employs a leaf spring cut out of the frame rather than a liner. It is stronger and more reliable than a liner lock, though closing still requires placing your hand in the blade path. Frame locks often have a steel interface on the lock bar to contact the blade tang.
Best for: Users who want enhanced strength and reliability compared to a liner lock.
AXIS ® Lock – Reliable and Ambidextrous
The AXIS® Lock mechanism uses a small, spring-loaded bar that moves back and forth across the blade’s tang to secure it in the open position. This design allows smooth one-handed operation, is ambidextrous, and offers excellent strength and reliability. The AXIS® Lock has become a favorite for tactical, EDC, and outdoor knives alike.
Classic AXIS® Deployment:
The Bugout® exemplifies the traditional AXIS® Lock, combining lightweight carry with a secure, easy-to-use locking system. The spring-loaded bar pushes over a cutout in the blade tang to lock the blade open. Typically opened via thumb studs, the AXIS® Lock provides intuitive one-handed opening, offering a balance of speed, strength, and consistency. Its ambidextrous design ensures reliable operation for both left- and right-handed users, making it ideal for everyday tasks, outdoor activities, or tactical scenarios where a dependable lock is critical.
Best for: Those who want a strong, versatile lock that’s easy to operate with either hand.
Flipper-Style AXIS® Deployment:
The Lowden™ showcases a flipper variation of the AXIS® Lock, designed for rapid, snappy blade deployment. To achieve this, the blade tang was redesigned to increase detent strength, allowing more potential energy to build until the blade breaks the detent and opens instantly. Thrust bearings in the pivot reduce friction, creating a fast, smooth action that feels effortless in-hand. This makes the Lowden™ a modern, fidget-friendly EDC knife with a precise, long-lasting spear-point blade and an ultra-modern ergonomic handle.
Best for: Users who enjoy a tactile, high-speed deployment with precision control, combining classic AXIS® reliability with interactive flipper action.
Photo: Max Jacobsen/@pnw_pew
AXIS® Assist – Speed with Safety
Benchmade Knife Company’s AXIS®-Assist technology builds on the AXIS® Lock by adding a torsion spring to the action to aid blade deployment. This gives you faster access to your knife while keeping the action controlled and safe. It’s especially useful in survival, camping, or heavy-use scenarios where quick deployment can be critical.
Spring-assisted blades must still be manually operated by the user, opening partway via thumb studs, a flipper tab, or some other portion of the blade, before the spring takes over. This bias toward closure differentiates spring-assisted mechanisms like AXIS® Assist from automatics, making them a good option for those living in areas with restrictions on autos.
The P.S.K.™ demonstrates this mechanism with assisted action for rapid, reliable blade opening. Its rugged construction and palm-friendly handle make it ideal for outdoor use, and the mechanism ensures smooth, repeatable deployment without compromising safety.
Best for: Outdoor enthusiasts and survivalists who need fast, dependable access to a folding knife.
Push-Button Automatic – Fast and Practical
Push-button automatic knives feature a dedicated button or switch on the handle. Pressing the button releases the internal spring, sending the blade into the fully open position almost instantly. This mechanism is intuitive, fast, and excellent for EDC scenarios where practicality and speed matter most.
The 9400 Auto Osborne is a prime example. It maintains the original 940 Osborne’s iconic EDC design, while adding a push-button automatic mechanism for instant deployment. This knife demonstrates that automatic action doesn’t have to be tactical to be practical — it’s all about speed, ease of use, and everyday functionality.
Best for: Everyday carry enthusiasts who want instant access to a reliable blade in a practical, familiar design.
Auto AXIS® – Tactical Power
Auto AXIS® knives combine the speed of an automatic opener with the strength and reliability of the AXIS® Lock. Pulling back on the AXIS® lock bar releases the blade with consistent power, making it a preferred choice for tactical applications where rapid response is required.
The Auto Adamas® exemplifies this mechanism with a rugged, tactical design built for in-hand comfort and dependable performance. Its automatic deployment ensures you have the blade ready instantly, while the robust construction can handle heavy-duty use without compromise. This makes it ideal for situations where speed, reliability, and durability are all critical.
Best for: Tactical users or anyone who wants the fastest deployment in a reliable, sturdy package.
OTF (Out-the-Front) – Compact and Ready
OTF knives feature a blade that slides straight out of the front of the handle via a spring mechanism. By sliding a switch, the user can perform a quick draw with instantaneous deployment, without the need to adjust the orientation of the knife in hand to open it. A single-action OTF requires manual retraction of the blade, while double-action OTFs operate via the slider in both directions. OTF knives are popular in tactical, law enforcement, and EDC scenarios where speedy response is critical.
The Shootout® demonstrates this mechanism with a lightweight, durable, EDC-friendly build. Its straight-forward deployment and secure retraction make it perfect for situations that demand immediate readiness, all while remaining compact and easy to carry. All Benchmade OTFs are double-action autos.
Best for: Users who want rapid, one-handed deployment and maximum portability.
Choosing the Right Mechanism
Selecting a knife mechanism depends on your needs, comfort, and intended use. Here are some considerations:
- Slip-Joint: Smooth, traditional operation; ideal for everyday carry and collectors.
- Flipper: Quick, controlled deployment; popular with enthusiasts who enjoy tactile engagement.
- Lockback: Incorporates a backspring lock to prevent accidental closure; simple, reliable, and safe.
- Liner Lock: Detent presses the liner against the blade to secure it; easily released for one-handed closing.
- Frame Lock / RIL: Stronger, integral frame spring secures the blade; highly reliable while retaining simple operation.
- AXIS® Lock: Balanced speed and security; versatile for general utility and carry.
- AXIS® Assisted: Rapid deployment without sacrificing control; great for outdoor use.
- Push-Button Automatic: Instant blade deployment with a button or switch; ideal for practical, fast, and effortless everyday carry.
- Auto AXIS®: One-handed automatic access by pulling back the AXIS® lock bar; suited for tactical or emergency situations where speed and reliability matter.
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OTF: Instant deployment and compact profile; ideal for self-defense or specialized use.
To help narrow down your options, Benchmade’s Knife Finder tool can guide you to the mechanism, blade style, and features that best suit your lifestyle.
Beyond choosing the right mechanism, having a reliable service partner is just as important. Benchmade’s LifeSharp program ensures your knife stays sharp, maintained, and ready for use, making it a dependable companion for years to come. With decades of expertise in precision engineering and quality materials, their knives offer consistency and trustworthiness that enthusiasts and professionals alike can rely on.