Oversized core to fit on collars and register boxes;Two layers of film encapsulate a galvanized or bronze coated wire helix;GREENGUARD certified;Available in master cartons;3"-4" 25 per master carton, 5"-20" 4 per carton;HUD /FHA standards 515.2.1, paragraph B;NFPA standards 90A and 90B;Meets most BOCA, City of Chicago, federal, state and local codes and standards;ETL listed/approved to UL 181 standards