Featuring a groundbreaking advancement in thermal insulation, the Sea to Summit Delta Insulated Mug uses an integrated, molded sleeve that actually insulates the liquid inside. Ultradurable food-grade Nylon 66 inner is BPA-free. Fitted ThermoSkin nonabsorbing sleeve insulates the liquid inside. Patent-pending Protex hex pattern base reduces weight and lessens the surface temperature so it can be held comfortably with hot liquids inside. Nylon 66 can withstand high heat and cold. Leakproof sipping lid-excess liquid flows back into the sipping hole because of the concave design of the lid. Well designed leakproof sipping lid has an ergonomic rolled edge and thumb grip with hang loop. Capacity: 16 oz. (473 ml). Weight: 4.4 oz. (125 g). Note: should not be used in a microwave