Product Info Catalog Hardware Builders Hardware Springs Extension Spring, 1-1/16-In. OD x 12-In. Extension Spring, 1-1/16-In. OD x 12-In. Request a Quote UPC: 38594003077 SKU: 681684 Model Number: C-307 1-1/16" OD, Extension Spring, 12" Length, .135" Wire Diameter, 6.49" Maximum Deflection, 66.2 LB Maximum Safe Load, Bulk With UPC.