Easy to use once you have mastered accurate measurement and the techniques. Be careful to use it the right way round elsewise the bevel is the wrong way. You MUST have an under sheet of card and work on a drawing board. Works fine to give any size aperture in the mounts.

I've been using this mount cutter to frame my photographs for a few years now, and I have to say that it is a pleasure to use. I believe it's dropped in price since I originally purchased mine, but this is the same model - the 600mm (24) long guide and 45 degree cutter. It has a very good non-slip base which helps to keep it in place as you cut, and if you mark out your path on the back of the mount board, you just line up the edge of the guide to one line, start the cutter with its clear, white mark on the perpendicular line at the bottom, and run up to the perpendicular line at the top and voila! You have your first edge cut. Repeat 3 more times, and you have a perfectly cut mount card ready to drop into a frame. Very neat. Very easy to use. My only reservation is that people with limited strength in their fingers - the elderly or people suffering from arthritis - may have difficulty maintaining sufficient pressure on the cutter with just a thumb, which is all the provision for grip that it provides. For this reason alone, it gets 45. That said, for anyone else, you really can't go wrong. Recommended!