Invented by an astrophysicist. Simply spin your Thumbler to activate a colourful light show - and then place it on the stand provided! Kids will love this pocket-sized gyroscope - but it's ideal for adults too! Perfect for the desk at home, at school or in the office. Fascinating science toy that you won't be able to put down. WARNING: contains flashing lights which may cause epilepsy in sensitive individuals. Batteries: 2xAG13 1.5v LR44 - not replaceable.