I need to replace both of these on a window, left and right.
Hello, thank you for posting,
Your balance assembly resembles the 15-180 pivot shoe that is compatible with the Series 190 coil springs. Please compare the dimensions below to confirm a good fit! These parts are interchangeable on either side of the window sash.
There should be a number stamped on the metal that indicates the weighted option needed. If there are no marking present, please provide the weight of the window sash to move forward! Also see the 15-186 balance clip and 15-182 balance bushing if needed. Let us know if you have any additional questions!
The dimensions appear to match the part you reference (15-180).
There is no stamp on the spring but the sash weighs 20 pounds. Which spring should I purchase?
Unfortunately we do not carry a single coil spring assembly that will support 20 pounds.
We recommend changing to a double coil set up, using (2) S190-540 coils springs with the 15-182 bushing per coil along with the 15-181 double support detent clip. Together with the other side, the coils will support 20 pounds of weight.
Please let me know if you have any additional questions!