Movement Differential:

The distance the button moves from the operate point to the release point (hysteresis).

Pitch:

The spacing between centers of adjacent leads/terminals.

Single Break:

A switch mechanism with one fixed terminal and one moving terminal that interrupts the flow of electricity at only one place. Please refer to the ITW Switches Characteristics/Circuits for more detail.

Normally Closed (NC):

A normally closed circuit allows electricity to flow through when the switch is in its free position; it prevents the electrical flow when actuated.

Pole:

The number of completely separate circuits that can pass through the switch at one time.