Best used in soils that retain water; suits all plants This soil aqua meter has plant water indicator that changes color depending on soil type - White indicates watering; blue indicates it's been watered The Aquameter is a leave-in soil moisture sensor pen that can be left in the soil for continuous monitoring, unlike other moisture meters that need to be taken out after each measure Set includes twelve refillable watering sticks (green) - Each stick has refillable replacement core that last for approximately 6- Award-winning product design, environmentally friendly, and maintenance-free (no battery required), Manufacturer: Aundhegrtt