3M(TM) Dual Lock(TM) Reclosable Fastener SJ3441 is a black, plain backed, no adhesive fastener. 3M(TM) Dual Lock(TM) Reclosable Fastener SJ3441 has 400 stems per square inch with an engaged thickness of 0.16 inches. 3M(TM) Dual Lock(TM) Reclosable Fasteners have been used extensively in transportation, electronics, business equipment, machinery, medical and sign and display markets. When the mushroom-shaped stems interlock, tensile strength is high enough to replace mechanical fasteners