I have three sizes for sale. 23" x 33" (it is 1/4" thick); 23" x 53" (3/8th inch thick); and 20" x 58" (it is 3/8th of an inch thick).
Let me know which you would be interested in. For your information, new ones cost approximately: the 23" x 33" one is around $50; the 23" x 53" one in 3/8" is approximately $145; and the 20" x 58" one in 3/8th of an inch thickness is approximately $130. Let me know if you are interested in any of these or all and what price you would be willing to pay. They are all clear and intact, except there is a small 'corner' chip on the 20" x 58" one.