Manual glass thickness measuring device for single and double glazed units ( IGs ) - designed to fit around PVC ( Vinyl ) and Aluminum frame doors and windows - also with reflective device for measuring each pane in a double glazed unit- mm only. Imperial and metric scale versions available. Easy, inexpensive tool for quick on-site checks ; great for truck stock and installers. Bohle exclusive product, made in the UK for Bohle England, now available in North America. Top seller !