This device turns most plastic bottles into a watering reservoir - perfect for when you are away from your beloved plants. The irrigation kit is gravity fed - it lets water flow out of the base using a tap system - unscrew the easy-to-use tap to achieve the required flow rate of water - the air is let in through a hole punched in top of the bottle. Now you can leave your plants, safe in the knowledge they'll be automatically watered correctly. Easy to use, the kit comes in a pack of 8 with full instructions. The cap measures 28mm across, so fits all bottles with a 25mm neck diameter – make sure to measure your bottle to ensure this dimension is correct.