3-Piece L099 Series coupling set includes two coupling Hubs & NBR rubber insert. 1" bore with 1/4" keyway and set screw on one coupling Hub. 3/4" bore with 3/16"keyway and set screw on Second coupling Hub. Compatible with Lovejoy, Martin, Browning, TB Woods, and other L-jaw couplers. Include - 1" Hub + 3/4" Hub + L099 Spider. General purpose straight jaw coupling hubs attach to motor and equipment shafts using a set screw or keyway. Two couplings of the same size are locked together with a compatible straight jaw spider. These hubs are interchangeable with other brands according to the coupling size identifier.