These brackets adapt your existing socket dust boot to the Z-Plus Upgrade from Carbide 3D for the Shapeoko 3. It uses 7mm and 8mm nuts mounted into recesses in the model for strength. The screws are off the original Suckit mount (5mm) and I used 4mm screws to secure the bracket to the Z-Plus.I print everything (pretty much) with carbon fiber filament and this seems to be extremely sturdy.