From Manufacturer
The Quick Release Locking Lever Clamp from Acratech will fit nearly all quick release plates that are Arca-type compatible. It has a locking lever and a precision laser-etched scale for accurate positioning. The quick release is made specifically for Acratech GB and GP-S ball heads. Stainless-steel construction and black anodized finish give this clamp a solid feel. A detent pin gives you extra security and the 15mm bull's-eye level helps to quickly position and level the head.
Weighs only 3.9 oz (11 g)
Quick action lever for fast and secure camera attachment
Lever lock provides extra security
Laser-etched precision centering scale
Detent pin for extra security
Adjustment knob makes it compatible with Arca-Swiss quick-release plates from different manufacturers
High friction adjustment knob--cannot accidentally loosen
Large bull's eye level
3/8"-16 thread with adapter for 1/4"-20 so it will fit almost all tripod heads
This clamp only works with Acratech GP and GP-S ball heads, and if you have a GV2, V2 or Ultimate Ballhead, you will have to send it in to Acratech have the clamp installed.