The Stabila 7' - 12' Type 106T Extendable Plate Level (35712) is designed for quickly and precisely positioning top and bottom wall plates plumb. They are extremely durable and accurate and are the best installation tools for tall doors, sliding glass windows, and custom kitchen cabinet installations. This plate level features positioning scales on both sides of the extension for fast set ups at various increments and a six sided keyed extension rail that delivers smooth and rigid operation. The accuracy of the two plumb vials and level vial are guaranteed for life.