Tankless Instant Hot Water Heater】No need to preheat before using the tankless water heater. As soon as you turn on the tap, the water flows with your desired temperature.NOTE: This product does not have a serial number. If you don't know how to install a water heater at all, it is recommended not to buy it. 【High Sensitive Touch Led Display】Comes with smart digital LED display high-definition large screen, freely adjustable the temperature between 30℃-65℃.NOTE: This product does not have a serial number. If you don't know how to install a water heater at all, it is recommended not to buy it. 【Multiple Security Protection】The natural gas water heater is upgraded with 12 protection methods to ensure your safety. Such as dry burning protection, over 65℃(149 °F) protection, leakage protection, etc.Note: In cold weather, if the water heater is not used for a long time, it is necessary to open the pressure relief valve to drain the residual water in the water heater to prevent the exchanger or water pipe from freezing and swelling. 【Energy and Money Saving】The hot water heater adjusts power input based on flow rate and temp setting in real time. Summer/winter 2 modes to save up to 60% on your natural gas costs.NOTE: This product does not have a serial number. If you don't know how to install a water heater at all, it is recommended not to buy it. 【Quality Material】Made with brushed stainless steel material, the natural gas water heater has the function of high temperature resistance, corrosion resistance. Built-in oxygen-free copper water tank, long service time.Note: This product must be installed with a ventilation and smoke exhaust pipe for normal use.