3M™ Dual Lock™ Reclosable Fastener SJ3541 is the easy and clear alternative to traditional fastening methods, such as screws, nuts or bolts. It is designed to deliver a durable, reclosable fastening solution (which can be opened and closed multiple times) which bonds to a variety of substrates including many plastics and low surface energy materials. - A black fastener with mushroom shaped stems that is backed with a rubber based pressure sensitive adhesive. Type 400 stem density polyolefin fastener which mates to type 170 or 250.