Good Morning,
You possibly have the Series 380 channel balance. I cannot be sure though because I am little confused on what you measured on the attachments and it is hard to tell the height from your pictures.
The Series 380 is made up of the
19-005 top and the
15-005 shoe. Click on each of those links and look at the close up product picture and compare it to your balance attachments. If they both match, then the S380 channel balance is what you need.
If it is indeed the S380 channel balance you will need the
S380-23.
I believe you will need the stamp option 2230 - which is for window sashes that weigh between 18 through 23 pounds. You can remove the sash from the window and weigh it on something as simple as a bathroom scale to be sure about the weight.
If your attachments do not match the S380 attachments, please submit a couple more pictures of each attachment for us to look at.
Also, remember that if you are replacing support balances for more than one window... you will need to check the balance in each window. They could be different styles and they will definitely have different channel and strength sizes for different sized windows.
I know this is a lot of information, I hope I did not confuse you. If I did confuse you, please let me know and I will try to clear it up :)
