These are bore gauges that automatically self-centre via a centring bridge. They offer you the following benefits: Easy to handle and adaptable to most bore gauging applications (6-400mm). A long plunger stroke gives you amazing accuracy. Interchangeable washers 0.5mm thick are supplied as standard accessories, so you can enable setting in small steps. Contact points are carbide (>18mm range), giving you high durability and wear resistance. A large grip reduces heat transfer from the operator by 50%.