This wheel is CNC lathe turned with a radius for better tracking on your grinder. It has a setscrew to hold the key to the shaft the wheel is a 3/4 inch bore which is the common shaft size on KMG and similar grinders. 100% made in the USA. It is precision machined forom 6061 aircraft aluminum. $48.00 plus shipping which is $7.35. This drive wheel will provide an increase in surface feet per minute of 25% more than the standard 4 inch drive wheel. The wheel is machined on both sides to reduce weight. Thanks, Larry Lehman