Spy Link This set is a great accessory for our Little Astronaut Set Space Suit, it easily clips to the front of the suit and can be worn under the helmet The transceiver unit has a clip-on feature so you can wear it on your backpack, shoulder bag, or belt This comes as a set of two, so you can stay in communication with a crew mate or mom or dad The set requires two 9-volt batteries not included For children ages 6+