CMP Self-Locking Trolley is made for heavy duty use. The rubber is vulcanized to the bottom and sides of the trolley to avoid chipping the edges of finished work pieces. This trolley is designed with self-locking jaws for maneuvering stone slabs around the shop, warehouse, or job site. The self-locking jaws clamping strength is proportional to the weight of the slab. The heavier the slab is, the stronger the clamping force makes.