Tormek WM-200 AngleMaster
This patented AngleMaster has two functions: You can use it to set the jig to the grindstone so that it grinds your tool to any desired edge angle from 10° to 75° and you can use it to measure an existing edge angle on a tool.
It is designed to work on any grindstone diameter from 250 mm (10") down to 150 mm (6"). You achieve an exact setting irrespective of the degree of stone wear.
The AngleMaster has two magnets for convenient fixing onto the housing of the machine.