#43 B 12 Tooth Sprocket with a 18mm ID, has two 1/4-20 set screws.
You can use one of the set screws and set with a drill dimple or the thru hole.
We opened a 5/8" ID sprocket to 18 mm or .701". No keyway.
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 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.
