3M? Dual Lock? Reclosable Fastener SJ3440 250 Black, 1 in x 50 yd 0.16 in (4.1 mm), 2 per e Bulk[click to enlarge]A plain backing, black with no adhesive. 250 stems per sq inch. Engaged thickness of 4.0 mm3M ? Dual Lock? 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? CloseQuick ClicksContact UsCatalog SearchProduct / 3M Id / UPCMSDS3M? Dual Lock? Reclosable Fastener SJ3440 250 Black, 1 in x 50 yd 0.16 in (4.1 mm), 2 per e Bulk 3M Id : 70-0705-2102-9GTIN(UPC/EAN) : 0 00 21200 65808 2