The rail mounting kit allows you to mount your 1900 PDA case onto boats or any round or flat rail up to a 2.0"(51mm) wide. The kit includes a heavy duty, shock-absorbing, adjustable mount which allows you to position your PDA in the best location and protect it from vibration. The PDA case is held securely while being easily and completely removable from the mount. This Yoke/Rail Mount Kit includes mount plus all necessary hardware.