29'm spiral balances

If the outer tube, not including the inner spiral, is 29" long, then you're going to need either our S600-29 or S900-29. The difference between these two spiral balances is the outer tube's diameter; the Series 900 has a tube that is 3/8" in diameter, whereas the Series 600 has a 5/8" tube, so compare both with your old balance to see which matches up. Let me know if you have further questions.