One problem with many optical slotted switches is that
they lack a convenient means to attach them to the body of the robot.
This switch, perfect for homebrew optical encoders (use with mouse
wheels or similar), provides a hole in the housing for easy mounting. It
also has a small profile so it can be mounted where other optical
slotted switches cannot.
They're new, with 4-inch leads. These are high-quality
Optek switches, unused, originally intended for industrial control.
Hookup diagram included.