Create a sturdy clamp base for your 38mm (1.5 inch) compatible mount or device with Arkon's SPCLAMP25MM. The adjustable clamp secures to tables, desks, counters, and other clampable surfaces up to 3.375 inches (86mm) thick. Screws not included. The 38mm (1.5 inch) ball is compatible with selected Arkon's Robust Series mounts, double-ball mount shafts, and adapters, as well as Ram Mounts Size C components.