HHIP 3900-0883 Mt3 Round Collet, 1/2" Hole Dia. 1/2" Drawbar End Threads: MT2: 3/8" - 16MT3: 3/8" - 16 Hardened and precision ground to close tolerance Morse taper: external Drawbar End Threads: MT3: 3/8" - 16 : Made of high grade tool steel. MT3 SHANK