NCB28 Nils thermal mug features both simple structure and original design! NCB28 is a thermal mug made of the stainless steel with a double wall due to which it keeps the temperature of hot drinks for 12 hours and cold drinks for 24 hours. What makes the NCB28 mug unique is the opening system with a locking option making the thermal mug extremely leak-proof. Consequently, you can take it anywhere and not worry about any leaks. To release the lock and open the lid just slide the opening button down, then press the button and there you go, the mug opens automatically!