unlabeled coil balance
Hello!
It looks like you have our 15-177 pivot shoe which uses the Series 152 coil springs. If you're not sure what coil weight to select, look for a stamp or code on the spring. If there aren't any stamps, you'll need to weigh your sash on a scale and divide the weight by the number of coils on both sides of the window to determine the correct strength option.
Those letters don't tell me what weight you'll need so you'll have to obtain the precise sash weight and divide the weight by the total number of coils in the window to determine the correct strength option. If you're still not sure, tell me the precise sash weight and total number of coils in the window and I can work out what you need from there.
The 26-446 and 26-466 are often used with the 15-177 pivot shoe but it will depend on the pivot bar you had originally.
I'm also not sure what you mean by "top roller". That's not a term we're familiar with. Can you clarify?