Climax Part 2C-100, Mild Steel, Black Oxide Plating, Clamping Collar, 1 inch bore, 1 3/4 inch OD, 1/2 inch Width, 1/4-28 x 5/8" Clamp Screw Effective on hard and soft shafts Design fully engages the shaft without marring 360 degree clamping force Easily installed where major disassembly would otherwise be required Black oxide provides some corrosion resistance