External clamp (often called Flicklock) mechanisms use a lever on the outside of the pole shaft that clamps down to hold your desired length. They're the most popular locking system for adjustable ski poles, and for good reason—you can quickly tighten or release them even with bulky gloves on, which is a huge plus on cold days.
Another big advantage is visibility: you can clearly see when the clamp is fully closed and secure, so there's no guessing. This makes them especially reliable for backcountry touring, where you're frequently adjusting pole length for uphill climbs versus downhill runs.
The main downside is that external hardware can collect ice or freeze up in very wet conditions, so it's worth occasionally clearing snow from the clamp. With basic maintenance—just keeping them clean and making sure they're properly tightened—external clamps are the most dependable choice for adjustable ski poles.