1 inch Socket Adaptor Plate with Amps 4 Hole Layout fits TomTom Rider 40 400 Dock Adaptor Plate with Amps 4 Hole Layout to 1 inch socket - allows you to attach your Rider 40 / 400 dock to 1 inch ball mount fixtures. Allows your Motorcycle GPS SatNav to to attached directly to bike mounting options using the 1" ball such as the RAM fork stem mount RAM-B-342 & the handlebar base RAM-B-231Z without having to use an arm. Adaptor plate only - NOT a complete mount Dock & mount NOT included