Catalog Doctor: Vitamin Maybe

2-ply: Great for portfolio use where space is critical or as a backing board. 1/32 inch.
4-ply: Creates adequate separation between your artwork and glazing [glass]. 1/16 inch.
8-ply: A window in 8-ply adds depth and drama to any image. Also ideal for larger photographs or artwork that need more structural support. 1/8 inch.