It's hard to find metric measurement tools in the US. Feeler gauges seem to universally have both SAE and metric units, but in reality, the blades tend to be made in units of 0.001", so they don't fall on nice, neat metric boundaries. My vernier calipers did not have enough precision so I did get a micrometer, but it is only calibrated in inches, and there were no metric ones available. You'd think with the number of foreign cars and motorcycles in this country that you could get some decent metric measuring tools, but no. (Wrenches and such are not an issue, of course.) Thus, the worksheet has all the clearances in both mm and in.