BT - CENTER ALIGNMENT COLLET CHUCK - METRIC Taper SizeBT-40 and 50 AT3 Taper 58-60 HRc N5 L L2 L3 (1) L1Ref. D D1 G (2) D2 J Designation Range L L1 L2 L3 D D1 D2 J G Hex Key(1) Hex Key(2) ADJ BT40 D70 ER32 2-20 129.5 52.5 102.5 92.5 50 70 62.5 M22x1.5 M16 4.0 5.0 ADJ BT50 D70 ER32 2-20 144.5 52.5 106.5 - 50 70 - M22x1.5 M24 4.0 5.0 The tools should be adjusted prior to initial use 813