3/4" x 14" with 3/16" keyway; Jackshaft kit used with #41 chain. Includes 10 tooth sprocket (3/4"ID), 14 tooth sprocket (3/4"ID), 2 bearing hangers, 2 standard bearings, 2 3/16" x 3/16" x 3/4" keys, and collar with 3/4" ID.