Made from FC25, fine grain cast iron; Trapezoidal-thread lead screw * Precision-ground guide bar for smooth, accurate travel and clamping; Base and bed parallel to 0.001"; Less than 0.002" jaw deflection at 2,000 lbs. clamping pressure; Jaw surfaces square to 0.002". * Sold iron construction with stress-relieved design: Replaceable jaw plates * Fixed jaw is grooved horizontally and vertically for holding round stock * Four slots for secure mounting to machine table