FeaturesMade of flame retardant neoprene, these new knockout plugs meet UL 514 flammability testProvide a rain tight, dust and oil tight reusable seal for electrical knockoutsNo tools needed to installJust push into hole and they snap-inNEMA 3R, 4, 6 and 13 boxes can be saved or reused whenever a knockout is no longer used-30 to 105 deg C temperature