Swarovski 42mm, 50mm, & 56mm Tripod Adapter means that you can attach 42mm, 50mm, & 56mm Swarovski binoculars to any tripod head with a 1/4""-20 threaded screw. The base of this Swarovski Tripod Adapter has a 3/8""-16 threaded hole with a video pin & supplied 1/4""-20 reducer bushing & allows the binocular's full interpupillary adjustment range to be retained.