Need help to purchase the correct balances.
Thanks for posting. I believe these are Series 385 Channel Balances; just make sure that bottom shoe depth is 1-3/32" instead of 1". That's what it appears in your photos, but pictures of measuring tape aren't always great to go by, so please confirm to be sure.
You'll then need to measure the length of the metal channel, without including the end nylon fittings in that measurement. While it looks like in your photos that length might be 33", I can't see if you included the fittings in that measurement, so I have no idea if that's the length you need. Please double-check this to be safe. Once you know the length you need, you need to pick a stamp option, which designates the strength of the balance. usually there is a stamp on the metal channel that indicates this; but if your balances have none, weigh the window sash that they support. You can then match the exact sash weight with the weight ranges listed alongside each stamp option under the product description of any channel balance shop page. Let me know if you have further questions.