The SWISCO Series 170 Coiled Balance Spring measures 3/4" wide and has a short tongue. This "constant force balance" is used in CertainTeed double hung window sash support systems.
Before you pick one of the options below, please refer to the stamp or imprint on your original spring. That should tell you what you need. If you're still not sure, or if you have no stamp, you can ask our experts for help here.