[Easy to use] No battery or needed, this water level meter is easy and convenient to use, plug and play. [Convenient observation] This water level indicator can display the water level to remind you of the water. If there is no water in the flower pot, the water level meter buoy sinks to the ground. When you fill the right amount of water, the buoy floats. [Important Reminder] If there is no water in the pot, the buoy of the water level meter is at the bottom. In this sense, pull the water level and the aquatic plants through the hole [Wide use] This water level meter is used for flower pots and is a perfect tool for indoor and outdoor use. Colour:White Material:plastic Size:20cm Package Contents: 10 x water level indicator Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.