This is a Dial indicator mount for Ender3 or Ender3 Pro, with the BL Touch metal mount. Screw direct in the BLT metal mount, this gives you a better Hot-Bed measurement level. In parallel, run a Grid Height GCode, you can do a quick first Hot-Bed level. I do this level adjunstment at least after 5 to 6 weeks, even if I don't use the printer.