I purchased this standard pulley to replace one that I had accidentally broke when I was removing it. Unfortunately, this is not a standard pulley. Although not specified, the keyway notch should be 3/16" wide with a 3/32" depth. The tolerance for the keyway notch should be +.0020, -.0000 width and +.016, -.000 in depth. The pulley I received had a keyway notch that measured 5/128" too small and the key would not fit. Rather than waiting another week for a replacement, I ended up filing the notch bigger to fit.