Window balance spring

Thanks for posting. Based on the measurements, it appears you'll need either the S900-30 with a red tip or the S400-30 with a red tip. The series you need will depend on the type of window you have.

If you window is a tilt window, you'll need the S900-30. If the window is a non-tilt, you'll need the S400-30.

Let me know if you have any questions.