This bracket is to house an induction probe (I used this one: http://www.amazon.com/Cylindrical-Inductive-Proximity-Approach-LJ12A3-4-Z/dp/B007Q813UA ) for use with ABL. It is designed to fit on a MakerFarm printer's extruder that has the fan holes freed up from an E3D installation. For more information on how to install ABL on your printer please watch this video: https://www.youtube.com/watch?v=EcGFLwj0pnA