RAM Garmin Montana 600, 650, 650t Holder with U-Bolt Mount, Double Socket Arm & Diamond Base. (sku 18577)RAM Garmin Montana 600,650, 650t Holder with U Bolt Mount, Double Socket Arm & Diamond Base. This is a double socket arm, zinc coated u bolt base, diamond adapter base and custom high strength cradle for the Garmin Montana 600, 650, 650t. 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 Montana mount to your optimum