caldwell window channel balances replacement

I see that your top attachment seems to have wings on the sides, but your bottom attachment doesn't. That is a hallmark of the Series 395 balance. You should check out S395-30 to see if it matches your balance, if your channel is 30" long. "29 9" is supposed to be a code that calibrates the spring strength, but it's obsolete nowadays. You need to weigh your window sash to account for this. The S395-30 webpage has a chart on it that will tell you which "option" to order, based on the sash weight.