Features: This module is a plant watering alarm - as simple as that. You put it into the soil near a plant and it emits a tiny chirp when the soil is dry, reminding you to water the plant. Chirp uses capacitive humidity sensing as opposed to resistive humidity sensing, this means, it does not make an electric contact with the soil, avoiding electrode corrosion and soil electrolysis and resulting in better accuracy and longer battery life. Special care has been taken not to make it yet another source of annoyance - Chirp will be silent when it's dark and will restrict itself from making too much noise. The alarm level can be set for each plant individually. As water is consumed by the plant, Chirp will detect the low moisture level and will start to emit rare short chirps. As more water evaporates, Chirp will increase the alarm rate. Chirp can detect if it's day or night by measuring the amount of ambient light and will not make noise when it's dark. Specifications: Color:Black Quantity:1PC Size:13.9*1.5cm Package Include:1PC Humidity Moisture Sensor Note: 1.Please allow 0.1-0.3cm differences due to manual measurement, thanks. 2.Please understand because of the light irradiation or computer display difference, so I can't guarantee photos and real color is 100% the same.