I live in an extremely old house, the byproduct of that are floors that incredibly warped and impossible to get an exact level on. My workbench was being supported on 3 legs by stacks of cardboard that slowly started to get on my nerves. So in seeking a level table, I designed this screw level and it solved all my problems. I found the easiest way to install these at the correct height (if you have something already propping the table up) is to use a pair of calipers to measure the depth between the top of the level's cylinder housing and the top of your prop, then use the bottom of the caliper to screw the disc into the cylinder until it reaches the same depth. Hope this comes in as handy for someone else as they do for me.