RAM® Ball Adapter with AMPS Plate The RAM-B-347 powder coated marine grade aluminium base consists of a 1 inch diameter rubber ball connected at right angles to a 2 inch x 1.7 inch square base. The base has four pre-drilled holes at each corner, making the universal AMPs hole pattern. This RAM part is supplied as standard as part of the mount kit with Garmin Zumos and TomTom Riders. This adapter/base is designed to hold the following devices:Garmin® zumo™ 350Garmin® zumo™ 400 Garmin® zumo™ 450 Garmin® zumo™ 500 Garmin® zumo™ 550 Garmin® zumo™ 660 TomTom Rider 2 TomTom Urban Rider Material:Powder Coated Marine Grade Aluminium Ball Size:1 inch Rubber Ball inch B inch Size