3 Piece 15″ 1.5mm X 60 Degree 25.5mm Best-Grip Hard Jaw Set ~ Supplies maximum concentricity on finish turning operations. ~ Groove width D is 1.055 (25.5mm). ~ Screw size E is M20. ~ Hole space F is 1.693 (43mm). ~ 3 holes. ~ 2 steps. ~ Step height S2 is 0.73. ~ Step height S3 is 0.73. ~ Width C is 2.44. ~ Length A is 5.63. ~ Height B is 3.39. ~ Can be used on Kitagawa, Samchully, Strong, MMK, SMW Autoblok, Howa & Hitachi-Seiki Chucks. ~ Taiki # TW-305A4 Supplies maximum concentricity on finish turning operations. Groove width D is 1.055 (25.5mm). ~ Screw size E is M20. Hole space F is 1.693 (43mm). ~ 3 holes. 2 steps. ~ Step height S2 is 0.73. ~ Step height S3 is 0.73. Width C is 2.44. ~ Length A is 5.63. ~ Height B is 3.39.