Glass Manufacturing design. There's a good chance that the BUFF (Big Ugly Fat uh, Fellow) will outlive all of us, and he's already been flying since1952, and for the military since 1955. This is the clean version of a similar design I made for Grandpa Buff fans. To see that one and other Grandpa Buff designs please click on "Grandpa Buff" at the top of the page . Dual wall insulated: keeps beverages hot or cold Stainless Steel, BPA Free Leak proof lid with clear slider