SUStee (5-piece set) is the perfect solution for all plant lovers who don't know how often to water their plants. What size SUStee to buy: Small - the diameter of the pot is less than 15cm; Medium - the diameter of the pot is from 15 cm to 25 cm; Large - the diameter of the pot is more than 25cm. SUStee detects water at the roots, no more dirty fingers and damaged roots trying to measure soil moisture with your fingers. Simple to use: leave the device in the pot and it will constantly monitor the soil moisture and indicate when the plant needs water. SUStee will change color from blue to white as soon as the plant needs water. Suitable for all plant types, soil types and pot sizes. SUStee's award-winning design is simple and minimalistic, so it doesn't detract from the beauty of your plants. SUStee is the only irrigation indicator based on the pF value (available water capacity). Professionals measure the pF value with expensive devices, but with SUStee you can also go pro. SUStee does not require batteries and is environmentally friendly. The SUStee inner core can be replaced manually. Depending on the type of soil used, the inner core lasts from 6 to 24 months. Materials: polycarbonate (outer body), non-woven cotton (inner core).