3M Dual-Lock Reclosable Fasteners – SJ-3542 170. 3M General purpose dual lock fastening systems. Black fastener with mushroom shaped stems, backed with a rubber based pressure sensitive adhesive. Designed to bond to many plastics, powder coated paints and other low surface energy materials, Opens and closes 1000 times before losing 50% of its original tensile strength. For our full range of 3M products, click here.