The RAP-299-3U serves as a mounting point for RAM 1″ double socket ball mounts. Insert the mount into any cupholder ranging from 2.57″ to 3.5″in diameter. KEY FEATURES Fits cup holders between 2.57″ – 3.5″ inside diameter 2-Hole AMPS: 1.912″ Overall Height: 4.75″ High strength composite Comes with two (2) #10 x 3/4″ Sheet Metal Screws Included are support fins that flex, making the cup holder base conform to most vehicle cup holders. Also included is hardware to attach a AMPS 2-Hole (Diamond) base to the cup holder base. Compatible with any vehicle cup holder with an inside diameter range of 2.57″ to 3.5″.