The RAM-B-347U base consists of a 1" diameter rubber ball connected at right angles to a 2" x 1.7" square base. The base has four pre-drilled holes at each corner, making the universal 1.5 x 1.188 (hole spacing) AMPS hole pattern.

This adapter/base is designed to hold the following devices:
Garmin® zumo™ 390LM
Garmin® 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 Aluminum

Ball Size:
1" Rubber Ball "B" Size

Note:
The "U" in the part number reflects product packaged in poly bag.