These are really cool Travertine Tile hand stamped coasters with a cork backing. It's natural stone so the colors may vary but they are available in light or medium shades.
They measure 4" x 4" and are heavy enough to stay in place without sliding or moving and absorb moisture really well. I use these on my wood furniture with no problems at all.
Because they are natural limestone like texture, holes and uneveness is to be expected. No two are exactly alike.
They can be wiped clean if needed, do not soak in water or place in the dishwasher.
These come as a set of two tied with jute.