Kids can write with these spy pens and turn on the secret light to read invisible messages - perfect for some spy adventure fun. Keep away from Children. Button Cell Batteries can cause severe or fatal injuries in 2 hours or less if they are swallowed or placed inside any part of the body. If you suspect your child has swallowed or inserted a button cell battery, call the 24-hour Poisons Information Centre in Australia on 131126 or in New Zealand on 0800 764 766 or contact your country's emergency department.