The leak-proof Stainless Carry Tumbler has a Flip Lid with safety lock that prevents the lid from opening accidentally. The lid is one-piece and gasket-free, and the stainless steel interior is SlickSteel polished. Its vacuum insulation will keep drinks hot or cold, while keeping the exterior from getting hot, or minimizing condensation. A perfect companion for business meetings or studying! Stainless steel vacuum insulated construction with superior heat and cold retention, leak-proof, gasket-free, one-piece lid is easy to clean and prevents the loss of parts (When used properly according to the instruction manual).