Its positi 1/4"-20 Socket Head Cap Screw, Plain Titanium, 2-1/2 in Length.Like platinum and gold, titanium is an element near the top of the galvanic scale and its resistance to corrosion of all kinds is legendary.
If you a These are structural, aerospace grade nuts with a minimum yield strength of 128,000 psi (880 Mpa).. These nuts are Grade 5 (Ti-6Al-4V) titanium and are TRUE TITANIUM(TM).They are stronger, lighter and completely corrosion free, even in saltwater.
It is also the most affordable and used in cooling systems, boat and ship #4-40 x 3/4 in Phillips Flat Machine Screw, Plain Titanium.Grade 2 titanium is unalloyed and the most common of all the grades of titanium.