Freehawk&reg; Garden Watering Spikes, Plant Waterer, Watering Stakes, Water Control Drip Cone Spike, Perfect for Vacation Plant Watering and Drip Irrigation Watering (4PCS) Proper for most bottle like Coca Cola and other drink plastic bottle, most suitable for soda drink bottleThis watering spikes have two diameter bottle cap. The bigger one's diameter is about 1.57 inches, the smaller one is about 1.18 inches. Any bottle cap's diameter approximate the size can match the spike. Ceramic Watering Spikes for Long time watering. The probes are made of ceramic material that will keep the watering at a constant speed. Please note that the watering speed is decided by different soil density, plant water absorption ability and other factor. EASY TO USE vacation plant waterer. First, prepare a bottle to fill water. Secondly, connect the bottle mouth to the connector. Thirdly, insert the water probes into the soil. Four Spikes for one pack. Economical watering system, usually a 500 ml bottle water can be watered for 3 days Automatic watering system for potted plants when you're away, Good quality ceramic watering spikes for longer time use