Slate Stone - Set of 4 coasters measure between 3 7/8" x 3 7/8" and 4" x 4" These coasters are perfect for a unique, custom gift for the HAM Radio Morse Code (CW) enthusiast. Each set is laser engraved onto slate material. There are felt pads on the bottom to prevent scratching furniture. Due to the natural material of these coasters, the color and placement may vary slightly. All items are made at time of order. All of our products are designed, engraved, finished, and shipped personally by my husband and myself!