This is a metal extruder holder for your Prusa I3 3d printer. Compared to the ABS/PLA printed plastic extruder holder, this metal one has better heat resistance. This one is for the MK8 sing extruder. You can use it on the geeetech Prusa I3 pro, Prusa I3 pro B, and Geeetech Aluminum Prusa I3 3D Printer.
For detailed dimension, please refer to the picture.