FP guide rods are CNC machined and feature a Black Nitride finish. I have found Black Nitride to be extremely durable and corrosion resistant.
These are a great replacement for the factory plastic guide rod in the Gen 1-3 Glocks and allow the use of different recoil springs to tune your gun to your ammo for smoother recoil impulse and better sight track.
NOTE Gen 4 and Gen 5 Glocks require the use of an FP guide rod adapter. (also available on this website)