The Hydropod is the most exciting and safest bottle rocket launcher ever. All you need is any 2 litre plastic soft-drink bottle with a bit of water in it and pump it up using the supplied air pump. By using a safety pull rope; you can launch a bottle up to 30 metres in the air. It has a built in safety-valve that releases pressure to help keep everyone safe from over-pressurizing the entire system. The Hydropod is built to last with high quality durable plastic. Includes air pump and safety pull rope. Warning: This is not a toy. This is intended to be an educational kit which demonstrates a science principle in a fun way. To be used under direct supervision of an adult. Read all instructions before you start.