Ratchets come in various sizes but 2" ratchet straps are the most common. These 2" ratchets are made of Type 304 Stainless Steel which contains Chromium to prevent rust from accelerating to the core of the material.
Chromium allows the stainless steel to form a passive "surface rust" that will not accelerate and therefore make these ratchets more suitable for the marine industry or high moisture applications. The surface can be scratched and the passive layer will form again to protect the core of the material.