It's a 12mm Tactile Push Button 40xx with Red Cap. The pins are normally open (disconnected) and when the button is pressed they are momentarily closed.
Features
Specification
| Package | 40xx |
| Insulation resistance | >100 MΩ |
| Length | 12 mm |
| Width | 12 mm |
| Mounting type | Through Hole |
| Cap Colour | Red |
| Country of Origin | China |
