Sea To Summit's Delta Insulated Mug features a groundbreaking advancement in thermal insulation. Constructed with an integrated molded Polyurethane foam sleeve that actually insulates the liquid inside the mug, it's unlike double walled mugs which only protect your hands but don't necessarily keep your beverages hot or cold. Well designed leak proof sipping lid has an ergonomic rolled edge and thumb grip with hang loop. Excess liquid flows back into the sipping hole because of the concave design of the lid. Microwave use is not reccommended early production versions incorrectly had a microwave safe symbol Ultra durable food grade Nylon 66 inner is BPA free Fitted, ThermoSkin non absorbing insulation sleeve Patent pending Protexhex pattern base Leak proof sipping lid Dimensions: 2.75 diameter x 4.25 tall. Volume: 16 oz. Weight: 4.4 oz.