3M Dual Lock Reclosable Fasteners Interlocking mushroom-shaped heads provide strong, reliable, and durable fastening that can be opened and closed multiple times. Mates with Type 170, Type 250, Type 400, or low-profile stem densities to provide different strength combinations. Strong fastener secures with an audible snap, verifying closure. An alternative to screws and bolts, this hidden fastener provides a snug fit and smooth aesthetic appearance. Pack of 2