100% acid free polypropylene! Here is a partial list of other games with this size cards:65x65mm, "Oathsworn: Into The Deepwood", and "Townsfolk Tussle" ** Note Game Titles and their intellectual property rights are and TM of their respective rights holders, no challenge to these rights is expressed or implied. Compatibility claims only extend to the physical size of the cards in each respective game and no claim to endorsement or authorization by the respective rights holders is expressed or implied by Sleeve Kings. Our products are compatible with the respective games only and all rights are reserved by the respective rights holders.