2-Pack CR10 Z axis T8 Anti Backlash Spring Loaded Nut Elimination Gap Brass Nuts for Upgrade Ender 3 Ender 3s Ender 3 Pro V2 CR-10 Tornado 3D Printer 8mm Acme Threaded Rod (Nuts)

Bolts dont line up on Ender 3 Pro. Essentially useless for my dual z set up. May try and swap for a new set, maybe it was a one off, otherwise the one star sticks for bad QA. Side note, on a test fit on the guide screw, it seems like this would lead to binding. Seems like the threads are off ever so slightly after a few twists you feels a good amount of resistance, then it lets off, then tight, then loose, etc etc. Again... could just be bad QA.

One of the couplers was burred and too tight. No free movement at all. The holes on the coupler do not line up with the holes on the backlash not. Cant be used together at all.

Holes spaced further apart than normal by about 0.5mm so won’t mount to frame.

Definitely grips on to the lead screw, use 2 on an ender 3 v2 with dual z-axis. Not sure if it does much but I would say it definitely does hold the lead screw better.

Doesnt fit the ender 3.

Most 3d printer noys just make junk toys; and will not have the skill to install these. Which is why there are a lot of bad reviews. Toy printers arent usually machinists. I found these easy to install and they stiffened the z axis a lot. The accuracy is great.

As described fast friendly service.

works great for my ender 3 v2, wanted some way for anti backlash for my ender and this worked perfect.

Good product for the price

Unable to install due to different hole spacing on the backlash spring. Also realized that it would not do anything. Its basically a type of cvd to eliminate screw wobble from affecting the gantry but it is only threaded on one side so the bolt has to go all the way through the coupler into the lead screw nut making them one solid unit. It needs threads on both sides so that it can be mounted to the screw and the gantry with short machine screws.