The RAP-274-1-GA39 consists of the EZ-ON/OFF™ dual strap base, swivel diamond adapter base aand custom high strength composite cradle for Garmin nuvi 3000 series GPS devices. Adjust the zip ties to attach to a variety of rails, from a minimum of 0.5" in diameter. With a press on the diamond adapter the EZ-ON/OFF™ system allows for the quick release of the Garmin nuvi cradle from the base. When connected, the diamond base can rotate, allowing for you to position the Garmin nuvi cradle for optimum viewing. This mount includes a 12 degree tappered shaft for tapered handlebars.