Pemko SiliconSeal Adhesive-Backed Fire/Smoke Gasketing, White Silicone, 0.4375" W x 0.3125" H x 17' L Designed for tighter frames Demonstrates extremely low closing force SiliconSeal is extruded from high-temperature silicone; effective between -58F and 450F. Seal begins compressing at 5/16"; Compresses to seal up to a 1/16" gap. Self-extinguishing and non-toxic; Unaffected by sunlight, ozone and ultraviolet rays.