Befenybay 2PCS 5mm to 8mm Aluminium Plum Flexible Shaft Coupling D20 L25 Connector Flexible Coupler for 3D Printer CNC Machine and Servo Stepped Motor（5x8mm）

one bolt came jammed and the head was already cammed out, the second one didnt have the relief cut all the way through so tightening is impossible

I bought two sets of these and both were bad. They are cheap so I did not go through the hassle of returning them again. I strongly recommend looking elsewhere. These are NOT the ones you should get. I struggled for days trying to figure out why the printer was failing, only to find out the problem was with the coupler. Bad on me for trusting a cheap product.

To tighten it you need to apply excessive force on the screws. There is the danger to destroy the threads on the top of the screws and not be able to remove it.

Just what I was wanting

The 5mm side for the stepper was to small. I ended up stripping the bolts to get it tight enough.

works great for helping z axis stress. Printer moves much smoother now after this and a dual axis upgrade

If your planning to buy this to solve z axis wobble, DONT! The hole is not centered and made prints come out worse than ever before! Poor manufacturing quality and not even worth $1 Look elsewhere!

Fit well but didn’t work as well as regular couplers. Rubber parts are not very flexible and there was still a lot of banding in my 3D prints with these. I had to switch back to normal couplers.

The children wanted to extend the shaft of the motor and in turn, go from an 8mm to 6 mm shaft. This did the trick.

Not much else to say other than these kept sticking on my dual z-axis Ender 3 Pro and causing terrible banding on prints. Woke up to a print I set overnight to see that one of them completely failed in the middle of the night and fell apart.