D3 Digital Thermo-hygrometer Product Overview Used to measure indoor temperature and humidity with precise digital display and comfort level indication. Key Features Indoor temperature and humidity display Comfort degree indicator Temperature unit ℃/℉ changeable Clear LCD display Technical Specifications Parameter Specification Temperature Range -10℃~+50℃ (+14℉~+122℉) Comfort Level Display Arrow points to "Comfort" when temperature 18℃~25℃(64℉~77℉) & Humidity 40%RH~69%RH.