RAM C Size 1.5" Ball Mount with 2.5" Round Plate AMPs Hole Pattern, LONG Length Double Socket Arm, 4.75" Square Plate VESA 75mm and 100mm Hole Patterns with Locking KnobThe RAM-101LU-D-246 consists of a long double socket arm, 2.5" diameter round base with the universal AMPS hole pattern and 4.75" square plate with the VESA hole pattern. The VESA plate contains a 75mm X 75mm and 100mm X 100mm hole pattern. Designed into the mount is a 1.5" diameter patented rubber ball and socket system with adjustment points at both socket ends of the arm. Rubber ball and socket technology allows for almost infinite adjustment and perfect viewing angles. This kit comes with a key lock knob that allows the user to lock the mount in one position, preventing other from adjusting or disassembling the mount without the use of the provided keys.