Alf, of course perceptive, but really, a bevel gauge, you traditionalist. It’s a bevel gauge that keys into the guide rail and has a stop to position the gauge against the wood. Hey this is measure once, cut once, we are talking of here. Blimey it must save minutes each time its used. Add those minutes up and you could have time for another cuppa in the day. And as taking time for tea means that relaxed and drowsy feeling which adds years to your life. Oh bother, I suppose if you fall asleep after the tea your back to before square one. (but maybe a longer life) QED. Buy the angle gauge and live longer.