Product Info Catalog Hardware Builders Hardware Springs Extension Spring, 9/16-In. OD x 8-1/2-In. Extension Spring, 9/16-In. OD x 8-1/2-In. Request a Quote UPC: 38594003190 SKU: 681734 Model Number: C-319 9/16" OD, Extension Spring, 8-1/2" Length, .054" Wire Diameter, 12.4" Maximum Deflection, 9.55 LB Maximum Safe Load, Bulk With UPC.