Stainless steel vacuum insulated construction with superior heat and cold retention; Heat retention: 144°F @ 6 hrs.; Cold retention: 48°F @ 6 hrs. Easy to use leak-proof, gasket-free, screw-off one piece lid is easy to clean and has a handle for worry-free carrying Special manufacturing technique applied to round the sip area for drinking comfort SlickSteel polished stainless steel interior minimizes odors and stains High quality 18/8 stainless steel, Made of BPA-free plastic and stainless steel