This part is a inner corner bracket for 2020 Al extrusion. It is meant to go with the 2020 Frame Corner found here: https://www.thingiverse.com/thing:1612368 These two parts allow one to build a very sturdy printer frame with just printed PLA parts and metric screws. General Specs: - Print at 40% for Strength, PLA is fine - Layer height at 0.2mm for screw hole/countersink accuracy - M4 Metric Screws with 2mm Countersink - Channel slots for tight and square fit - Each Aluminum piece is contacted by three screws in a triangular patter for max rigidity