RAM Mounts Tough-Mag Magnetic Ball Mount The Ram-B-Mag66U and Ram-B-Mag88U from RAM Mounts offer efficient and easy mounting on metal surfaces. These mounts come in 2.6 (66mm) or 3.5 (88mm) diameter base sizes, featuring Tough-Mag Ball Mounts with a threaded post and RAM's 1 (Type B) size attachment balls. They are equipped with an N35 grade magnet, strong and durable, and a rubber coating to safeguard the metal surface from scratches. Specifications: Magnetic plate size 2.6 (66mm) or 3.5 (88mm) diameter Ball / socket size B (1) Ball mount: 1/4 - 20 threaded post Weight Capacity: Standard use: 2lb Heavy-duty use: 1lb Materials: Marine-grade aluminum Rubber