window balance

Thanks for posting. I am confident we can help, but to be cautious, can you show me pictures of the nylon fittings on both ends of the metal channels? I want to be absolutely sure we know what you're working with, as we've had a number of balances assumed to use standard fittings, which ended up having small but significant differences. Confirmation would be best, just to make sure we get you the right parts. Many thanks. 

This appears to be either a Series 351 or Series 390 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best. For the 29" balances, choose a stamp option of 2830, and for the 18" balances, choose a stamp of 1720.