Progressive, RDC-36, Heavy Duty Galvanized Steel Door Safety Chain and Spring for Exterior Doors for 34" - 36" Doors. Galvanized steel butt welded chain. Para-rubber covering. Galvanized extension spring, approximately 8" long. Designed for Exterior Doors to Withstand Strong Winds. 3" X 3" Galvanized Plate to Install on Door with Included Thru Bolts. 1-3/4" X 2-1/2" Galvanized Plate to Install on Door Frame with Included Screws. Mounting and Fastening Hardware Includes Self Drilling Screws for Steel Door Frames. Easy to Follow Instructions.