"The RAP-B-166-2-GA41U consists of a 2.75"" twist lock suction cup base, double socket arm and high strength composite cradle. The suction cup, twist lock base is designed to have a strong hold on glass and non-porous plastic surfaces, including RAM adhesive disks. Designed into the mount is a 1"" diameter patented rubber ball and socket system with adjustment points at both ends of the socket arm; this with a twist of the arm knob, allows you to move the mount to your optimum viewing position."