3M SJ3550 Dual Lock Tape sort 25mm x 46m3M Dual Lock Reclosable Fastener SJ3550CF Type 250 3M Dual Lock Reclosable Fastener SJ3550CF is a Type 250 reclosable fastener with approximately 250 mushroom shaped stems per square inch. The product is supplied as a pressure sensitive adhesive backed roll measuring 25 mm x 45. 7 m (two rolls per case as per product specifications). The backing is made of polypropylene, and the adhesive is acrylic. Material and Function Type: 250 reclosable fastener