Specification: Material: plastic metal parts Size: 11 * 7cm/4.33*2.75'' Color: as shown in the picture Power supply: 2xAA batteries (NOT Included) Recommended age: over 5 years old The experimental principle is as follows: When working with electromagnet principle, it can send out continuous bell Warm Tips: 1. When assembling the products that need to use the circuit, pay attention that the red wire is connected to the positive pole of the battery box; the blue wire is connected to the negative pole of the battery box. 2. All products do not carry batteries, pigments and glue. The color of accessories is random and does not specify color. Please read carefully before purchasing. 3. It contains small accessories and sharp objects. Children should be accompanied by adults. Please take care of children and avoid swallowing. Note: Please allow 1-3mm differs due to manual measurement. Due to the different display and different light, the picture may not show the actual color of the item. Thanks for your understanding. Included: 1 X Bell Model 1 X Single Pole Switch 2 X Battery Boxes 4 X Wires