Each coaster measures 4 inches in diameter and is almost 1/2 inch thick. There is a thin piece of cork sheet on the bottom. Some had to be trimmed to size. Because each coaster is created by hand, there may be little differences from one to another. The one(s) you receive may be different than those pictured. Coasters were created using Artresin and a mold. While I try my best to eliminate them, there may be some imperfections such as bubbles. Cork is a very porous item.  This price is for one coaster only.
ArtResin is non-toxic resin that is safe for food contact. The heat generated from a hot mug will not damage the resin surface. However, hotter temperatures such as that produced from a frying pan or casserole dish straight from the oven may well be too hot for the resin surface, so I do not recommend coasters be used for hot plates. Clean using a damp cloth.  ArtResin is recommended for use up to 120° F. Resins tend to yellow over time. Store in a dark place when not in use.  These pieces are offered at a discount since some yellowing has already occurred. It does not change the function of the coaster.