Can I start by saying that this product is a superb idea and the engineering principle of it is very sound. Here's the but - it is not very accurate and suspect this is down to the cheap spirit level and holder used. This is a shame as the rest of the tool is superbly engineered and has a real quality finish. I now use it as a rough setting guide only. Do not rely soley on this for tool height setting or you will break tools and ruin your work. I am going to try and re-engineer this to improve it when I have the time - but that will have to wait. In conclusion - a good design which, unfortunately, is poorly executed.