Searching for Block & Tackle Window Balance - 27 4 HR

Thanks for posting. Your balances appear to be either the S380-28 or the S385-28 with a 2740 stamp. To confirm which on you have you'll need to measure the depth of your bottom shoe. It will either be 1" or 1-3/32". If it differs, please let me know.

I've included the diagram below to use for reference.

Comparison of the S378, S380 and S385 balance shoes.