Tumblers are doubled walled stainless steel and they keep drinks hot or cold for a very long time. I use mine daily and LOVE them!
I use high quality glitter for extra sparkle and seal it with FDA compliant epoxy that is food grade. The epoxy covers the glitter and decals so you'll never have to worry about those coming off.
Tumblers are hand wash only. Do not soak them. Dropping can cause cracks, do not leave in hot cars.