This tilt sensor module is used for inclination indication. It is based on mercury switch which contain a blob of mercury. When the body move to a specific angle (usually around 30°), it shorts two pins and thus closing the circuit and tilt is detected and the signal output is high. 

The simplicity of this sensor makes them popular for toys, motion detection alarm, gadgets and appliances. 

Specifications

• Voltage supply: 3-5V
• Output: Digital
• Dimensions: 21 x 13 mm

Tilt detection sensor arduino code and connection