The Maars Skinny Steel is a 20oz double wall 18/8 stainless steel thermal bottle with a powder coated finish that protects against chips and scratches. Copper vacuum insulation keeps drinks cold 24hr, hot 12hr. Comes with a clear push-on lid and matching straw. Non-toxic and BPA-free. Note for folks customizing these cups. The Skinny Steel 20oz are slightly tapered (top 9.417", bottom 8.722").