Description
In the Williams Manuals this is labeled as a “Backbox Glass Binder”, now this may be incorrect, as I have seen many errors in manuals over the years.
It’s mounts into the back lower channel, then the rear keyed access panel slips into it. So it holds the lower edge of the metal access panel in position.
Measures 21-3/4″ long and 3/4″ wide, with a 5/8″ deep channel.
Williams: 3A-7234