3M™ Dual Lock™ reclosable fasteners consist of a continuous polyolefin film backing with mushroom shaped stems protruding up from the backing. When pressed together these mushroom shaped stems interlock to provide you with a strong reliable attachment. There are three different stem densities (170, 250 and 400) offered with these fasteners, referring to the approximate number of stems per sq-in. These 3M™ Dual Lock™ reclosable fasteners SJ3440, SJ3441, SJ3442, SJ3460 and SJ3461 have no adhesive backing and are used in specialty applications where unique attachment methods are necessary. 3M™ Dual Lock™ reclosable fasteners were developed and work best when held rigid and flat therefore all data provided in this document is typical data for when the product is securely anchored, held rigid and lays flat. The strength will vary depending on the applications and how well the fastener is attached. It is up to the end user to determine if this product meets the application needs. Dual Lock™ 7100136223, Mushroom Shaped Non-Adhesive Reclosable, 50 yd Length, 2 in Width, 0.16 in THK Engaged, Black, Polyolefin Backing, 200 °F Maximum Operating, 400 sq-in Stem Density, Resistance Properties: Temperature