same manufacturer two windows 1/2 inch wide ribbed one pair at 35 inches long spring stretch 19 3/8 inches spring relax is 15 3/4 inches one pair at 29 inches long spring unknown
Tom from SWISCO responded:
August 15, 2018
Hello! I think these are available on our site. They look like Series 770 balances. Take a look at the details of our S770-35 and S770-29 balances. I believe these match what you need.