1" x 1", clear, dual lock reclosable fastener, hundreds of mushroom shaped stems interlock when the 2 sides are pressed together, snap announces that the fastener is engaged, apply at temperatures above 50 degrees Fahrenheit, 10 degrees Celsius, make sure surfaces are clean & dry, do not use on car mufflers, furnace exhaust tubes, or anywhere temperature exceeds 300 degrees Fahrenheit, 149 degrees Celsius.