#43 or 410 B 11 Tooth Sprocket with a 5/8" ID, has a 3/16" keyway & two set screws. The sprocket width is .875" or 7/8". 1/2" Pitch x 1/8" width teeth. Finish: Black Oxide
You can use any of the chain, master links / connecting links, offset or half links that have 1/2" pitch x 1/8" width.
NOTE: You can also use #43 Sprockets with 410, 410H, 415 or 415H chain that has a 1/2" pitch x 3/16" width. The chain would be a 1/16" wider then the sprocket but it will track and wear just fine.
