5 in, Coupling Construction One-Piece, Coupling Material Stainless Steel, Coupling Outside Diameter 2 1/2 in, Different Bore Sizes No, Keyway Depth 1 Not Applicable, Keyway Depth 2 Not Applicable, Minimum Bore Diameter 1 3/8 in, Keyway Width 1 Not Applicable, Keyway Width 2 Not Applicable, Maximum Bore Diameter 1 3/8 in, Maximum Speed 3,500 RPM, Maximum Torque 825 in-lb.