Product Info Catalog Hardware Builders Hardware Springs Extension Springs, 5/16-In. OD x 5-In., 2-Pack Extension Springs, 5/16-In. OD x 5-In., 2-Pack Request a Quote UPC: 38594002872 SKU: 639781 Model Number: C-287 2 Pack, 5/16" OD x 5" Extension Spring, .031 Wire Diameter, 8.78" Maximum Deflection, 3.78 LB Maximum Safe Working Load, Polybag.