RAM Mount RAM Double Ball Mount w/1/4"-20 Male Thread - Short Arm [RAM-101AU-B]RAM Double Ball Mount with 1 4" 20 Male Thread Short Arm The RAM B 101AU consists of a double socket arm, one 2. 5" diameter round base with the universal AMPS hole pattern and universal camera camcorder base. The universal camera camcorder base consists of a 1" diameter rubber ball connected to a 2. 5" diameter round base with 1 4 20 camera thread. The male thread matches most standard camera and camcorder female threads found on the bottom of the