Channel balance replacement

Question

I have 2 windows that need channel balances. These are aluminum single hung non tilt windows. Approximate sizes are as follows

36x34 channel balance 34"
36x28 channel balance 28"

I can't find any names or stamps on the balances and do not know the weight of the windows. I found a stamp on the smaller window sill but all other stamps are not legible.
I have included pictures of the top and bottom nylon glides and nylon window stop and label

User submitted photos of a window balance.

Paul · Accepted Answer

Please see our Series 380 channel balance and 18-124P top sash guides. You will need to weigh your sash on a scale to determine the proper spring strength for our balances. Without any stamp on the original hardware, that is the only other way to determine what you need.