The RAM-D-202U-RM1 consists of a 2.25" ball connected to a 3.68" diameter round base that contains pre-drilled holes that connect to Raymarine devices listed below.
RAM® Double Socket Arm with RAM® Pin-Lock™ Security Nut
RAM® Double Socket Arm
RAM® Double Socket Arm with Jam Nut
RAM® Horizontal Swivel Mount with Socket Arm
RAM® Vertical Swivel Mount with Socket Arm
RAM® Horizontal Swing Arm Mount with Single Socket Arm