window slide tension part

Thanks for posting. This looks like an older version of our Series 140 Coil Balance assembly. A 7 stamp indicates you likely need the S140-7 7 pound assembly. This means your window sash should weigh around 14 pounds, but if you want to be safe, weigh the sash to confirm this. The 'L' likely means this is for the left-hand side of the window as well, so you'd need the S140-7 with the left-handed option. Let me know if you have further questions.