410 B 15 tooth sprocket has a 1/2" pitch x 1/8" wide teeth with a 3/16" keyway & two set screws.
This sprocket has a counter boar ID with 3/4" width at the recess and .875" wide over all for the hub of the sprocket.
These sprockets are made to be used with 410, 410H or #43 chain that is 1/2" x 1/8" but can also be used with the wider 415, 415H (1/2" pitch x 3/16" wide teeth) and even with the wider #41 chain that is (1/2" pitch x 1/4" wide).
You can use wider chain with thinner sprocket teeth as long as the pitch of the chain is the same.
