Tilt-Window Spiral Balance Question

Question

Have removed old balance and is 29" long (tube only) But the diameter is 1/2", not 3/8" or 5/8" (please see photo).  Can I use a different size, and if so, which is best?

Bob · Accepted Answer

I believe this reads as 9/16". It's hard to tell with these spiral balances that have older plastic tubing, since they warp over time; but I think this is likely an S600-29 with a Black Tip option; but double-check to be safe.