Keep your plants healthy and watered while you are away. The beautifully coloured glass spheres slowly let the water seep out to water a plant for up to 14 days. Easy to use - you just fill the sphere and press the spike into the soil next to a plant. It does the work for you. Comes in a set of six. Each sphere measures 15.2cm by 6.4cm (6" by 2-1/2").