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）

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

no spring back as with the traditional couplings. Nice tight, true turns when engaged!

After a few uses the coupler was stripped and kept coming off the z motor.

They would not clamp to the stepper motor shafts of my sidewinder X1 no matter how much I tightened the bolts.

Quality of coupling itself and screws is really bad. I would avoid as it is not worth the hassle of ruining your motor is the coupling seizes and you are unable to get it off.

Holes out of alignment. They wobble. The hole for the motor is skewed enough to be visible. Probably done free hand on cheap drill press. I payed alot for quality got junk. Shame.

These coupling did not last thru the first minor jam on m Tops cnc

Took me some time to figure out what was causing the banding on my print. When I took the lead screw out and looked at the shaft coupler while it spun, you can easily see the top piece wobble, thought it was just a bad z-screw initially, but after replacing that first, it had to be the coupler.