The RAM Quick-Gripwith Twist-LockSuction Cup consists of a 3.3″ diameter suction base, double socket arm and spring loaded cradle for supporting most phones. The Twist-LockSuction Cup is designed to have a strong hold on any windshield, glass and non-porous surface. The double ball and socket design provides adjustment points at both ends of the socket arm with the turn of a single knob, allowing you to set your phone to the optimal viewing position.