Clear Backer Boards are precision cut to size and the thickest boards found anywhere in the Industry! Clear Backer Boards are produced from Polyethylene Terephthalate (PET) which is a safe, non-toxic, strong, lightweight and flexible material that is 100% recyclable. These Clear P.E.T & Acrylic boards are acid-free and archival safe with a protective peel-away film on both sides which allows you to beautifully display the back of your comics. The only difference between the two materials is the acrylic boards are stronger and a bit clearer than the P.E.T boards! Comic Pro Line's Clear Backer Boards are quickly becoming a favorite of comic collectors worldwide! Once you experience the quality and thickness of these boards, you will never use anything else! They are truly that good!