Searching for My channel has no option.

Thanks for your post, Fred. It sounds like you know what Series channel balance you are looking for. But if it's ok with you I would like to ask for you to clarify a couple of things for me to ensure we are on the same page with one another. You identified your balance as being a Series 380 channel balance. It sounds like you are mentioning that they are 20' in length. I'd like to ask for you to measure them again because I see the stamping, "20 3", you provided which tells me that your balance is actually 21'. Please reconfirm that measurement. Make sure to measure metal to metal excluding the nylon attachments. If it is 21 inches, then the S380-21 should work for you. 

As for the option, you would choose the 2030 based off of your stamping which holds a sash weight of 12-15 pounds. Does that sound about how much your sash weighs? If you are unsure, you can always remove your sash and weigh it on a scale to confirm. I hope this has answered all of your channel balance questions. If you would like for us to offer our suggestions, send us photos of your balance and we will take a look. 

Ahh, I'm glad Manuella asked for more information. If your metal channel length is 20-5/8", then you have a balance that will have to be specially made. Just to be 100% sure, I would like you to take a picture of the top and bottom nylon attachments and a picture of the metal clip at the end of the cord. That will allow us to confirm exactly what you need.

Can you also confirm how many you were looking for? You said you needed 6/20 but I'm not sure what quantity that indicates.