Its an inductive proximity sensor with internally digitized analog output. It senses the metal underlaying the build plate surface, so if you aren't running a PEI coated spring steel build plate its probably not going to work, though it *may* be suitable for *thin* PEI, glass or Garolite, over an aluminum heat spreader plate, with some loss of accuracy. Its only usable with Klipper or similar controllers as analog bed levelling sensors aren't supported in Marlin based firmware.