4 Pieces of solid black rubber interlocking floor mats pack. SuperMats Superlock Interlocking Rubber Flooring System - 3/8" Thick Rubber Jigsaw Puzzle Style Exercise Floor Mats and Exercise Equipment Mats for Custom Gym or Exercise Areas. We recommend that you use this heavy duty rubber flooring on top of concrete, tile, or most any other hard surface. The SuperLock Flooring System is made from recycled rubber and bonded with urethane binder which encapsulates each piece of rubber for long life and provides resistance to wear. SuperMats Super Lock Interlocking Flooring System is the latest quality flooring system by SuperMats. The Super Lock Flooring System offers an interlocking rubber floor system that consists of a single design piece that can be trimmed easily with a straight edge or utility knife - making it easy to adjust the size of your workout area and still have a professional rubber floor system!