Product Info Catalog Hardware Builders Hardware Springs Extension Spring, 5/8-In. OD x 8-1/2-In. Extension Spring, 5/8-In. OD x 8-1/2-In. Request a Quote UPC: 38594003176 SKU: 681726 Model Number: C-317 5/8" OD, Extension Spring, 8-1/2" Length, .091" Wire Diameter, 4.05" Maximum Deflection, 36.9 LB Maximum Safe Load, Bulk With UPC.