The RAM-B-149Z-GA16U consists of a zinc coated u-bolt base, double socket arm, diamond adapter base and custom high strength composite cradle for the Garmin eTrex. Designed into the mount is a 1" diameter patented rubber ball and socket system with adjustment points at the base and cradle. With a twist of the arm knob, you can move the Garmin eTrex mount to your optimum viewing position. Included in this package is hardware that will accommodate rails from 0.50" to 1.25" in diameter.