> Model no. 1291 To determine the change in length as a result of warm storage, the marking gauge can be used to mark exact parallel circles on the outer surface of pipe segments with a diameter of up to 400 mm. It consists of a prismatic jig with a spring-loaded bar, which carries two hardened marking rollers. The marking rollers are fixed at a distance of 100 mm and have spikes. It is also possible to adjust the rollers to other distances if desired. Users of this product may also be interested in: Forced air oven