Sprocket 5/8 inch ID 410H Machined for most of our outside drive & Inside drive Gear Boxes with the shorter shaft. These are milled to a 1/2 inch thick. Pick from 18 or 19 teeth. These sprockets have a 1/2 inch pitch x 1/8 inch wide teeth with a 3/16 inch key way. These sprockets can be used with the wider 415H and 41 chain. Be sure and Click on the size you need.