Product Info Catalog Hardware Builders Hardware Springs Extension Springs, 7/16-In. OD x 3-1/2-In., 2-Pack Extension Springs, 7/16-In. OD x 3-1/2-In., 2-Pack Request a Quote UPC: 38594001639 SKU: 681221 Model Number: C-163 2 Pack, 7/16" OD, Extension Spring, 3-1/2" Length, .047" Wire Diameter, 3.5" Maximum Deflection, 8.47 LB Maximum Safe Load, Polybag.