How Locks Work Internal twist-lock
When you rotate sections in opposite directions, a plastic expander inside one shaft cams against the joint’s inner walls, keeping the pole segment from slipping. Twist-locks are the strongest mechanism available and rarely loosen accidentally, as other devices can. But cold can prevent them from locking/unlocking reliably, and they’re harder to adjust with mittened or sweaty hands.
External lever clamp
Closing the lever tightens a stainless steel, aluminum, or plastic band that clamps the two segments together; opening it lets you adjust pole length. These locks are reliable in freezing temps, but support less weight than twist-locks before collapsing (300 pounds max versus 400). Still, that’s more force than most hikers apply. Some need ample force to close tightly.
A spring-loaded button on one pole segment locks into one of several holes on the other segment. This mechanism is fast to operate, but it’s not as strong, since the buttons can enlarge the holes over time, compromising the lock. Also, the predrilled holes mean you can’t fine-tune the length as precisely, and pressing the buttons can be tricky with gloves.