High quality aluminum alloy and rubber materials ensure durability The ball size is 25mm/1" of diameter compatible with RAM Mounts B Size Double Socket Arm and other brackets that fit this size ball Bracket is a 3-in-1 functional design, it can work for most of walkie-talkie, speaker microphone with back clip, and for all CB/mobile microphone with round knob Package Includes: 1*3-in-1 Bracket with 25mm ball 25mm 1" Ball Adapter