Looking to replace two pairs of spring balance

Thanks for posting. Is the metal channel, not including the nylon attachments at both ends, 26" long? If so, see the S378-26, S380-26, or S385-26. The only difference between these channel balances is the 'depth' of the bottom nylon shoe. See below. Measure your old balance's shoe depth to see what matches best.

Comparison of the S378, S380 and S385 balance shoes.

You then have to choose a stamp option, which reflects the balance's strength. If there's no stamp on the old metal channel, weigh the window sash the balance supports. You can use that exact weight to choose the right stamp code. Let me know if you have further questions.