Dual Lock Reclosable Fastener (250 pin / 400 pin) - One Strip: 1" by 1 ft
Dual Lock is the strongest fastener system on the market, designed for high performance in automotive, aircraft, and building construction. Unlike Velcro, there is no "hook" or "loop", as each strip is open on one side and able to be fastened to any other strip. Dual Lock has up to 5x the tensile strength of industrial strength hook-and-loop products and resists harsh wet/dry and hot/cold cycles. Dual Lock is the only reclosable fastener strong enough to allow you to install mass loaded vinyl in your vehicle.
At the "Strong" level, every strip you receive is the 250 stem/sq in version of Dual Lock. At the "Strongest" level, half of the strips have 250 stems and the other half have 400 stems/sq in. The "Strongest" level has 50% more tensile strength than the "Strong" and is what we use to hold up mass loaded vinyl.
To get the most bang for your buck, Dual Lock strips should be cut somewhere between 1" x 1" squares to 1" x 6" rectangles depending on the weight of the material being fastened. One strip is 12" long, and can be cut into two 1" x 6" pieces for a total of 6 square inches of coverage. For a rough estimate of the total amount of Dual Lock needed per sheet of Second Skin mass loaded vinyl or foam, see below:
How to Tell Dual Lock 250 from 400
Type 250: Stems are in a wave pattern (approximately 250 stems per square inch)
Type 400: Stem heads are almost touching (approximately 400 stems per square inch)