These glue-resistant nylon cauls are the reverse or negative image of a typical pyramid bridge wing. They lock in place on top of the delicate pyramid shape, creating a secure flat clamping surface for regluing an old bridge or new installations. I glue a lot of old and new pyramid bridges with hot hide glue so time is of the essence. These cauls will help you and the bridge feel more secure while you zip through the reglue with less trouble. Each kit contains two cauls.