PGT Single hung windows

I'm not sure what you have, unfortunately. There are dozens of different balances with that stamp. It's not a product code or anything, it just indicates the strength of the spring.

In order to figure out what Series this is, I need you to remove an undamaged version of this balance from the window and show me clear pictures of the top and bottom nylon fittings. I will also need to know the dimensions of these fittings.

Lastly, you may want to get the weight of your sash. Your old stamp indicates a sash weight of 37 pounds, but we always like to triple check such details just to be 100% sure. 

Thanks! Based on your combination of top and bottom fittings, my top recommendation is the S395-30. This comes with a 19-005 top and 15-001 bottom, so as long as those match up then you should be good to go.

Additionally, based on your sash weight of 36.8 pounds, I'd suggest using the 2965 stamp option we offer for this product. Two balances with this stamp can carry 35 through 39 pounds, which should be perfectly sufficient for your application.