Series 160 Coil Balance Quote

Thanks for posting. If you are certainly you have the 1/2" wide Series 160 Coil Balance springs, we do not carry a version that has a 12 pound spring weight--but you could use the S160-06 6.5 spring and S160-05 5.5 pound spring, a pair for each side of the sash. This would give you that 12 pounds of support on either side of the sash, and 24 pounds of support total. Let me know if you have further questions.