I sharpen with the Blackstone FBV system here in Livonia, MI. I've been using the Blackstone machines since the opened for biz about 13 years ago. We were one of the first to own the FBV and spinner system in Michigan. The 90/75 cut is used by 95% of my customers. Anyone using the ROH cuts 9/16, 5/8 or 1/2 are using 90/75. All but one of my goalies are using 100/75.