Supplied complete with: restraining rod, center point feeler, 4", 8" & 12" straight feelers, 4", 8" & 12" curved feelers, fitted case. Designed for quick and accurate centering of a work piece or fixture. Operates at any angle. Use on vertical and horizontal machines. Use for internal and external diameters. While spindle rotates, the centering indicator remains stationary and always faces the operator. Probe ball: 1/8" diameter. Capacity: Internal: 5/32" to 4-1/4" dia. External: 0 - 4-1/4" dia. Speed: Not exceed 800 RPM Approx. Locating accuracy to within 0.00025" of true center.