https://thevacuumpouch.co.uk/product-type/foil-backing-boards/
Foil Backing Boards | The Vacuum Pouch Company
backing boardsthe vacuumfoilpouchcompany
https://acecomics.co.uk/shop/comic-backing-boards-collectorline/
Comic Backing Boards (Collectorline) - Ace Comics
Feb 23, 2023 - By Collectorline 178 x 264mm These will fit Collectorline Comic Bags, and Self Sealing Bags, and are calcium buffered for protection.
backing boardscomicace
https://www.gaylord.com/Preservation/Photo%2C-Print-%26-Art-Preservation/Matting-%26-Framing/Matting%2C-Mounting-%26-Backing-Boards/Rising-Buffered-White-Conservation-Matting-%26-Mounting-Board/p/HYB09275
Rising Buffered White Conservation Matting & Mounting Board | Matting, Mounting & Backing Boards |...
mounting boardrisingwhiteconservationmatting