i have used this costly product only a few times and it is warped and wrinkled!!!..impossible to use properly now, cannot hardly see thru it. it cost 18 dollars, guaranteed 5 years but of course i don't have the reciept. now i was looking at a new one in the store, same price, it came with a warning 'materials in this product are banned in california and are found to be cancerous' any comments on this are welcomed.