I use EcoPoxy brand resin, which is plant-based, biodegradable, and non-toxic. These coasters contain a variety of different seashells and sea life, including starfish/sea stars, sand dollars, abalone shell pieces, scallops, and other shells. They are made of casted clear epoxy resin and have a very slight blue mica sparkle to them. Bumpers are included on the bottom to prevent scratching. They are super light weight and very durable. All shells/items within the coasters are hand picked and arranged. The detail of the tiny sea life is breathtaking. Casting the shells/sea life in resin really makes it all pop and the slight mica powder shimmer adds to the beauty. Each coaster has a lip around the outside perimeter to help prevent moisture leakage. Item Type: Handmade Dimensions (per coaster): 4" x 4" x .25"