Inductive Sensor 12mm LJ12A3-4-Z/BX Three Wire NPN NO DC 6V-36V 4mm range

Widely used as a PINDA sensor on various 3D Printers.

Inductive Sensor 12mm LJ12A3-4-Z/BX Inductive Proximity Switch Three Wire NPN Button Normally Open DC 6V-36V 4mm

Will successfully operate at 5V - check partnumber against your old sensor to be sure that it is the correct type for your 3D printer. 

Sensor range (4mm) is based upon a ferrous ( ie iron or steel) surface it may be a lot less on other surfaces such as Aluminium or FR4 (PCB) materials.  

These type of sensors are not generally recommended for Glass surfaces.