Every catalog product ordered is manufactured with the bore size specified by our customer. The bore sizes shown for Mach III catalog products are MAXIMUM bores size available for that product with a standard keyway. Mach III also supplies METRIC bores and keyways and can supply non-standard keyways.
If you have a non-catalog unit, the bore and keyway sizes are typically specific sizes associated with the special part number assigned to that product. Contact engineering if you need to order a non-catalog product with a different bore or keyway size than you have currently.