The QM178 Security Rule provides a quick relative height reference measuring tool as an individual passes by a door with a security rule in place. The chart is easily mountable on door jams and window frames. The adhesive backing is semi-permanent.
The security rule is 1 7/8 inches wide by 37 inches high and begins measuring at 3' 8 inches and measures up to 6' and 8 inches in height. Height can be quickly read down to the one-half inch.