Wheelchair Rail and Tube Mount with Extension and Camera - Camcorder Round Threaded Stud Base (sku 21546)Wheelchair Rail and Tube Mount with Extension and Camera Camcorder Round Threaded Stud Base. This mount features a tool less Small Tough Claw base with 1" rubber ball, two double socket arms, a double ball adapter for extra length and articulation together with a 1" rubber ball connected to a round plate with 1 4" 20 camera thread. The male 1 4" 20 threaded steel stud will connect to any standard female thread found The round plate provides extra