1-Hour Class 350 Fire with Impact UL label. Tests include 1 hour exterior file exposure at 1700°F, a 2000°F explosion test, and a 30 foot drop to test impact integrity. Made in USA ETL Verified Listed Water Resistant means files are designed to prevent water damage resulting from sprinklers and fire hoses. Four letter-size 31" deep file drawers built with high sides for use with hanging folders and 1 follower block per drawer. Product is equipped with UL listed high-security Medeco locks. This lock resists picking and drilling, and keys cannot be duplicated except through FireKing. This means access to your vital records is limited to authorized key holders only. Fireproof insulation is 100% gypsum reinforced by a 1” x 2” lattice made of 14-gauge galvanized welded steel wire, providing complete peace of mind from fire, impact, or explosion.