We have two different balancers for two different sized windows. One is marked 2020 and has about a 21" metal channel.
The other is marked 2620 and has about a 27" metal cannel.
All the other hardware is the same between the two and are represented in the photos.
We need about 8-10 of the 2020 and 12-14 of the 2620 models. The house was built in 2007. There is a sticker in the frame of a few of the windows that says Code: C-582-1, Rating: H-R25, Series: 700SH, MST: 4060.