With adhesive sticker at the bottom, this practical product is easy to install. Compact and exquisite product can be a good decor for car, home, office, etc. The thermometer and hygrometer are mechanical structures, no battery required. It is made of good quality ABS material, durable to use. The diameter is 4cm It is suitable for home, car, office, indoor and outdoor use. Item Name: Humidity Temperature Meter Material:Glass,Steel,ABS Batteries: Clock Battery: 1 x Button Battery(Included), Thermometer/Hygrometer Battery: No Battery Size Details: Diameter: 4cm/1.57" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 X Car Clock/Thermometer/Hygrometer