The Acratech GP-s Ballhead with Lever Clamp is an updated version of the existing GP-s head. Rather than a rubber knob, this model features a locking lever for securing the Arca Swiss-style clamp that constitutes the quick-release element.
Featuring first-class construction, the GP-s Ballhead also functions as a gimbal head for lenses up to 400mm f/4.0, and it can be positioned upside-down to function as a leveling base for panoramic photography. Even if you're operating on rocky or otherwise uneven terrain, you can pan absolutely parallel to the horizon, so you won't need to carry a separate leveling base to create accurate stitched panoramic imagery.
With all that functionality, the GP-s Ball head is designed with a small base diameter of 2.08" to allow it to be used with travel-type tripods whose legs fold up 180°, reaching to the top of the tripod head. The smaller base diameter allows the tripod legs to fold more compactly.
The ballhead also features a bull's-eye level on the quick-release clamp and a detent pin, which prevents the plate and anything attached to it from sliding out of the quick-release clamp when it's partially loosened. Lightweight at only 0.9 lb, the GP-s Ballhead supports loads over 25 lb from any position, including tilted 90° and mounted upside-down.