Why stainless steel? you ask....
1. It just looks better than black oxide hardware. (In our opinion ;)
2. The reliability of knowing that after running your RC in the water or mud, you will see no rust or corrosion. Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film (the rust) is active and accelerates corrosion by forming more iron oxide, and due to the greater volume of the iron oxide this tends to flake and fall away. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal's internal structure, and due to the similar size of the steel and oxide ions they bond very strongly and remain attached to the surface.
3. We supply A2 and 18-8 Stainless hardware. 300 series stainless steel having approximately (not exactly) 18% chromium and 8% nickel. "18-8" and "A2" both have superior corrosion resistance to 400 series stainless, is generally nonmagnetic, and is hardenable only by cold working.
Better question...Why NOT Stainless Steel???