6 3-Jaw Self-Centering Lathe Chuck, Front Mount, Two-Piece Reversible Jaws. Two-Piece Reversible Jaws; Jaws are composed of top and bottom pieces; American Standard Tongue and Groove Style; ISO3442. Highly durable; Steel inner mechanisms are quench hardened to increase toughness. Plain back; Requires a fitted backing plate to mount to your lathe’s spindle; CME fully machined backing plates are available. 160 mm Chuck Diameter; 45 mm Through-Hole Diameter; 3 mm – 55 mm Clamping Range; 55 mm – 145 mm External Clamping Range. 130 mm Recess Diameter; 5 mm Recess Depth.