As the title says, I have a collet chuck that came with the mill... but I have no idea what sort. Its on an MT3 taper. The chuck can handle anything up to 0.7" (17.7mm) through the nut and the internal opening for the collet in the main body is .88" (22.4mm) at the top. The nut is about a 1.25" (32mm) thread. The outer dimensions are 1.89" (48mm) dia and from the top of the nut to the gauge line is 2.6" (66mm). The nut has a steep taper, the chuck body a very shallow one.