Newcomdigi Vacation Plant Waterer Auto Drip Irrigation Watering Ceramic Watering Stakes Self Watering Spikes Perfect for Potted Plants and Plant Watering Stakes Indoor&Outdoor Use 2 Pcs Dark Green Economical: Economical watering system, usually a 600 ml bottle water can be watered for 5~7 days. Convenient: Ceramic Watering Spikes for Long time watering. Automatic watering system for potted plants, especially , when you're away from home , or taking a vacation . Easy Use: Proper for most bottle like Coca Cola and other drink plastic bottle, most suitable for soda drink bottle . Two Sizes of Bottle Caps:This bigger one's diameter is about 1.89 inches and the smaller one's diameter is about 1.1 inches. Therefore any bottle with that diameter bottle much can match the spikes. How does water come out? The probe is made ceramic material, the water comes out slowly through the ceramic part.