Our 12" Big Easy jaws are for gripping on the rims or inside of bowls, platters and hollow forms, and are optional equipment for our Easy Chuck. They have a maximum grip diameter of 10", the maximum expanding dimension is 11-1/2". When jaws are fully closed, the o.d. is 10-3/4", when jaws are fully open the o.d. is 12". Your lathe must have a minimum swing of 12" to use these jaws. The 12" Big Easy Jaws include 4 base jaws, 4 jaw plates, 8 dovetail grippers and 1 5/32" T-handle hex wrench. Snap-Lock Technology allows jaws to install in about 30 seconds! Works only with the genuine Easy Chuck. Easy Chuck not included.