Learn the science of connecting a circuit with this comprehensive but easy snap together kit and build your own door buzzer. Place this behind your door to keep intruders out of your room. Children can see the internal workings through the clear case. Fun and educational at the same time; Links to science, physical processes ks 1 & 2. Learn how to build a working burglar alarm. Learn to wire a simple circuit. Transparent case allows you to see the workings. Size H21.5, W16.5cm. Batteries required: 2 x AA (not included) plus . For ages 8 years and over. WARNING(S): Not suitable for children under 3 years old. Only for domestic use. To be used under the direct supervision of an adult.