It is, as near as I can see, foolproof. The front end of the handle incorporates two sloped guides that will give you a 25-degree cutting edge. You place the blade flat on the guide and sweep it across the rod. Work Sharp says the rod is fine grit; I think it's closer to medium. I couldn't get the finely honed edge that enables you to shave hair, but I could get a very sharp, fairly coarse edge that will cut damned near anything else with about 3 strokes on either side of a dull blade.