MadameHardyHi @MadameHardy,
It did take a bit of searching but I was able to find it. https://bigboardenterprises.com/bigboard/
Towards the bottom of that page, you can find some info on the aptly named Little Big Board:
-Add a Little BIG BOARD (18" x 48") along side of the BIG BOARD and create added surface to hold a large project (quilts, curtains or table clothes). This helps to prevent drag stitch from occurring.
-The Little BIG BOARD is great for smaller sewing rooms or flip down wall ironing boards.