ER-style one-piece R8 toolholder collets for Bridgeport and other knee mills grip drills, taps, reamers, end mills, boring bars, and special round-shank endworking tools. Each holder accommodates a range of ER-style collets. Maximum round-tool capacities are 3/8 in. (ER16), 25/32 in. (ER32), and 1 in. (ER40). Each collet has a TIR of 0.0005 in., or less.