2 PCS 8mm x 500mm (0.315 x 19.69 inches) Vigorous Linear Motion Rods, Case Hardened Chrome Shaft Linear Rail Rod Shaft for 3D Printer, DIY, CNC - Metric h8 Tolerance

Very smooth and straight. These are rigid as well, which is important at 450mm. No binding or noise from the bearings. Really impressive given the price.

Verry nice Quality , strong for my project of a rock tumbler.....

The skin is very hard, use a carbide insert to turn or cut. The core is about 40-50HRC, can drill and thread without annealing.

Super sturdy. Can easily support my full body weight without permanently deforming. I have this rotating in a set of two bearings about 2.5 feet apart, and it's critical that the axel stay very straight, and this rod has done awesome. Hard enough that the set screws don't chowder the surface when they are locked in place, but not so hard that the set screws just slide over the surface.

Perfect 10 mm straight and sturdy

This bar is the right diameter to bend a cetme flat around and buying it though amazon was the cheapest option. It didn't flex in the press, just worked out great.

Superior quality, excellent choice.

This shaft is incredibly good value when compared with other linear guide shafts available from industrial supply houses like McMaster. The diameter is within the h8 tolerance, just as stated. The shaft is case-hardened and can be cut with carbide parting tools. The shaft center is soft and can be drilled and tapped with conventional HSS tools.