atat Camera specific, Arca Swiss compatible quick release plates have long been regarded by professional photographers as the best method of attaching a camera or lens to a tripod head. The only problem with this system is that if the clamping knob is accidentally bumped and partially loosened the plate and its attached camera can slide out. This rarely actually happens but, the thought of it bothers many users and would be users of this system.
Acratech has developed a spring-loaded detent pin that projects into the pockets or windows that are cut into the bottom of most manufactures (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.
When using this system quick release plates must be inserted and removed by opening the clamp and inserting or removing the plates from the top.
Older style plates like the original Arca Swiss that do not have pockets or windows on the bottom can still be used with this system but the detent pin will not be very effective.