This coaster is uniquely beautiful with its petri dish effect. Striking vibrant colors come from alcohol ink that is dropped in freshly poured resin and mix around to cause a psychedelic effect. The measurements for this coaster are L 4x W 4 1/2x D 2/3. This is water resistant and quite sturdy, so you can put a variety of cups on it. Also a perfect gift for a friend or family member.