Trish used to sell this shirt in her bird store next to Smokey's shop, but it has been out of print for years. We decided to reprint it for the holidays this year and if it sells well, we may keep it around. The front has a detail of one of the hot vapor patent drawings and the back has a large exploded patent diagram. It's printed in black on a heather grey pocket t-shirt that is 98% cotton. The only way to make sure you have this shirt in time for Christmas is to order now. We may not be able to get more printed in time.