Some blower hubs can be purchased with a second keyway that is 180 degrees from the standard keyway to inprove the shear strength of the assembly. If you have a blower application, this second keyway is highly recommended. Blowers put a lot of stress on the snout of the crank and the crank hub key can shear off under this load. Eagle can machine a second keyway in either 1/4" or 3/16" for a minimal charge. Just ask for a blower keyway to be cut and specify which size you need.