ReliaBot 10mm x 600mm (.3937 x 23.62 inches) Case Hardened Chrome Plated Linear Motion Rod Shaft Guide Metric h8 Tolerance

Appears to be fine. I didn't measure it out to see if its exactly 400 mm. I'm using it for a dual z axis upgrade on my Ender 5, and it fits the bill. It's a bit cheaper than Misumi, but it still seems to be quality. I was annoyed mildly that they were shipped separately - I had to gigantic boxes for two rods, but I guess you could say that it's packaged well.

I needed these for a 3d printer mod. They arrived well packaged. The rods are smooth and straight. Thanks

Using this as an axle for a pivoting solar panel.Seems to be high quality and is very hard. Set screws on drive gear could not even dent it. Had to grind a flat spot on shaft to lock the two together.

Used to fabricate a piece for ND testing. Works good and has held up.

This was the best rod.

Worked great, it's a perfect fit