Coasters = Acrylic on ceramic tile coasters sealed with resin; full cork backing on all; sets of 4. There are no two alike. The price difference has to do with the type of resin used: standard resin - $20; high-temp heat resistant - $24. Trivets are either 7x8 hexagon ceramic tiles or 6x6 square ceramic tiles. Both are sealed with high-temp heat resistant resin. Can be commissioned in your prefered style and chosen colors.