The Acratech GV2 Ball Head / Gimbal Head with Lever Clamp is an updated version of the existing GV2 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.
The GV2 is a sturdy, heavy-duty, yet compact ball head that is similar in design to most conventional ball heads (unlike Acratech's unique Ultimate head). However, the GV2 model can be locked down when the head is in the 90deg. orientation (in the "gimbal slot"), which effectively turns this ball head into a gimbal-style head. This allows the camera to pivot around its center point. A bushing on the ball's stem and a pin on the bottom of the ball enable this smooth rotation - free, gimbal-style movement.
The built-in industry-standard Arca-Swiss-style quick-release clamp makes it compatible with the many different plates available from Arca-Swiss, Kirk, Wimberley, Really Right Stuff, Foba, Novoflex, etc. The clamp also features a spring-loaded detent pin that projects into the pockets or windows that are cut into the bottom of most manufacturers' (Acratech, Kirk, Really Right Stuff, etc.) quick-release plates. This detent pin will prevent the plate from accidentally sliding out in the event that the knob is partially loosened.
In addition, this model uses a "leveling" q.r. clamp, which features a large 15mm bullseye bubble level that extends out of the side of the clamp. The GV2 features a low-profile design and sports all-rubber knurled knobs that are comfortable to use, even in extreme weather.