Size: Front: 2 inches x 0.39 inches; Back: 1.8 inches x 0.39 inches. Design: Made of metal, stylish, durable, anti-corrosion. High precision: The advanced humidity sensor maintains +/- 0.5% accuracy. Minimal maintenance: This hygrometer does not need to replace the battery. Service & Notice: We guarantee the quality of our products. If you have any questions, please feel free to contact with us, we will offer the best service. Enven though hygrometers have been calibrated before being sent, you had better do calibration before using in case of inaccuracy.