window channel balances

Thanks for your photos. Based on what I see here, you have either our Series 380 or Series 385, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

Concerning your stamps, a "27 C" stamp corresponds to a 28" long balance with a 2730 option, while "21 B" corresponds to a 22" long balance with a 2120 option. Your first stamp definitely looks like a 27 C to me, not 27 E, but that's something you'll need to confirm before you buy anything.

If you have any doubts that these options are accurate, you can always weigh your sash on a scale to get its weight. We have a detailed weight chart on each Series 380 and Series 385 store page that tells you exactly how much weight each option supports.

Comparison of the S380 and S385 balance shoes.