The average shower stall mat sold today is too small, measuring 21 x 21 inches, the same size that it was in the 1940s. The average size of a standard shower has grown by over 50% during that same period. The XL 27 x 27 Anti-Slip Mat was designed to cover more slippery surfaces for the modern shower stall design. After use, simply rinse and hang to dry. When needed, machine wash in warm water with a mild detergent. Air dry.