This is a 3-terminal microswitch, with a small push-button. This switch has a great 'clicky' sound to it, and a nice tactile feel.

Features:

•     - Max 4A 125/240VAC
•     - 2 mounting holes
  
•     - Long mechanical operating life
•     - Contact resistance: less than 0.2Ω
•     - Insulation resistance: 500Ω minimum @500VDC
•     - Rated to 10000 clicks
  

Dimensions:

•     - 0.63x1.1x0.42"
•     - Weight: 5g