The RAM-B-347U base consists of a 1in. diameter rubber ball connected at right angles to a 2in. x 1.7in. 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 400
Garmin zumo 450
Garmin zumo 500
Garmin zumo 550
Garmin zumo 660
TomTom Rider 2
TomTom Urban Rider