This is a touch sensor to detect the contact with charged bodies like human fingers and so on.
These sensors are used in touch screens, you can use it to implement your own touch screen, and your security system.
Another application is to create an electric safety switch, that prevents people from electrification, so whenever an electric conductor is touched by a charged object (human), the electricity will go OFF.
Color: red + blue
Working voltage: for DC 5V
Material: PCB + Brass
Dimensions: 43 x 16 x 15 mm
Weight: 3 g