It may be 416 stainless, or 303 stainless.

416 is a cheap martensitic variety with lower resistance to corrosion than the 300 series. It machines beautifully. Many linear motion components are made of it (ballscrews and LM guides).

303 is similar, but has lower machinability and does not respond to heat treatment.


You may find 416 in printers. The ground and polished rods that form the base of their LM are typically made from it.