Spaces your tripod head above your tripod for additional clearance. Great item for tripods that have a bigger top than the head being put on it.
The Riser has a 2 3/8" (16mm) diameter by 1" (25mm) height.
It has a 3/8 -16 threaded hole in the bottom and a 3/8 -16 stud on the top.
Also included is a 1/4 -20 bushing for the bottom.