Be equipped on CNC machines, diamond finger bits are mainly used for sink cutout and other purposes. Different diamond segment formulas for cutting different stones. Please let us know the material to be cut when placing orders, like hard granite(black galaxy), medium-hard granite, marble or other stones. The connection is usually 1/2" gas thread or shank. The diameter is usually 22mm or 25mm, with a working length of 40mm, 50mm or 60mm. Sunny Superhard Tools can provide you with 2 different types of CNC finger bits - Normal Type and Enhanced Type. Enhanced type costs more but has higher efficiency and a much longer lifespan than the normal type. Please check the difference as follows: Sunny finger bits list: Finger Bit Type Diameter Working Length Connection mm mm Normal Segment φ22 L40 1/2" Gas Thread, Shank L50 L60 φ25 L40 L50 L60 Enhanced Segment φ22 L40 L50 L60 φ25 L40 L50 L60