The Opto Endstop, which is very accurate and easy to use . When the light is blocked, Opto Endstop will immediately output the digital control, and the LED will be on. Opto Endstop adopted standard electronic brick interface, therefore, it is easy and convenient to plug and play.
Operating voltage: DC 5V
Important note on application with 3D printer
RepRap's Cartesian axes all need a datum (also known as home position or end-stop) to reference their movements. At the start of each build each axis needs to back up until the datum point is reached.
For RepRap, you can use one opto-switch for each axis to define its position. The opto switches also help to protect the machine from moving past its intended range and damaging itself.