The mechanical endstop uses a lever switch to detect when it is activated. The switch is wired up so that when activated, it pulls the signal to LOW. There is also an LED on the board that will light up when the switch is activated.It uses a standard 4 pin .100″” pitch header and accepts a standard, old-style CD-ROM audio connector cable. Brand new and high quality. The endstop is a reliable endstop / switch solution for any type of 3D printers and other CNC and/ or 3D tools. Package Includes: One Piece new CNC 3D Printer Mech Endstop Switch For RepRap Makerbot Prusa Mendel RAMPS1.4 SKU: PGI-0012030 Category: 3D Accessories