Extensive compatibility: Attic Spreader Hinge Arms Compatible with Werner Attic Ladders, including Models Mk 1 thru Mk 3, A2208 A2210 A2508 A2510 W2208 W2210 W2508 W2510 WH2208 WH2210 WH2508 WH2510 WH3008 WH3010. Note: Only applicable to models manufactured before February 2006. Upgrade design: Upgrade the attic ladder hinge arms with electrophoretic coating technology. The three-layer galvanizing process s excellent wear and corrosion resistance. The ladder spring is made of high quality steel wire, reinforced by special treatment, durable, not easy to oxidize and change color. Easy to install: 55-1 Attic Ladder Spreader Hinge Arms not only comes with detailed instructions, but also has perfectly fitted spring and parts, so there is no need to worry about any installation problems.