The RAM rail mounting bracket for the Garmin eTrex 10/20/30 uses a zinc coated u-bolt base with a 1” ball that will accommodate rails from 0.50" to 1.25" in diameter, a 2.47” double socket arm and a cradle specifically designed to fit the Garmin eTrex 10/20/30 models. The rubber ball and socket design allows almost infinite adjustment so you can view it from any angle. Mount it to the grab rail on your boat, handlebar on the ATV, bicycle or motorcycle; this mount will hold up on any adventure. The mount is made of powder coated marine grade aluminum, is ultra durable, dampens shock and vibration, and comes with a Lifetime Warranty. RAM mounts are Made in the USA.