One of your most important tools now fits inside your toolbox!.. New folding design with removable axle insert. This tool offers the easiest way to accurately adjust the most important setting on your bike. Metric scale on one side and inch scale on the other side. Red numbers against white background for high visibility. Will work with mini or full size bikes. Can be used to check front or rear sag. Posse Sag Scale is very easy to use. The axle insert goes into the rear axle and the Sag Scale is simply held vertically up against the bike