I have upgraded my Ez3D Phoenix printer's bed carriage. I used 4 - M3 bolts 4 - M3 Nuts 4 - SK8 8mm CNC Linear Rail Shaft Guides 4 - SCS8UU Linear Motion Ball Bearing CNC Slide Bushing 2 - 8mm Stainless Steel Rods This y-axis switch holder mounts under the aluminum bearing. I used 4 - M3 bolts 4 - M3 Nuts 4 - SK8 8mm CNC Linear Rail Shaft Guides 4 - SCS8UU Linear Motion Ball Bearing CNC Slide Bushing 2 - 8mm Stainless Steel Rods This y-axis switch holder mounts under the aluminum bearing. You have to slide 4 M3 nuts into the side holes and then use a long M3 bolt. I did not use the thread that the bushings came with, which is why I recommend M3 bolts so they can goo all the way through the nheat plate, springs, bushing and reach the M3 nut in the switch holder. (50mm+)