Supply Voltage : 3.3-5V; Operating Temperature : below 80℃; Filament Diameter :1.75MM(1-2MM); Filament Presence : LOW; Filament Absent : HIGH(equal to Supply Voltage); Install:; Please install the unit after the spool and before your extruder. Fix it on your printer and along with the path of filament is recommend. Pay attention to the direction indicated by the arrow on the body. Inserted the 4mm PTFE tube to both side of the unit for guiding the filament and help to reduce the friction. Cable color: Red : 3-5V; Yellow/Blue : Signal; Black : GND; Connections: Servo pins always have the right pins:5V,Ground and Signal. Most endstop pins will have the same 3 pins,and sometimes only Signal and Ground.If you only have these two,there should be a 5V somewhere else on your main board. In theory you can choices any input pins on your main board for signal. Expansion: If you want install more than one unit on same printer just connect the unit one to each other then connect to the main board at the end.They just parallel connection on the circuit Level. So the signal output can't tell which one is run out actually but you can check the flashing LED on the unit to find out.