Shimano Antares DC Unit Fixing Screws Compatible with 21 and 23 Antares models. Made of lightweight and rigid titanium. This listing is for 2 sets of 2 screws, for a total of 4 screws. Hex wrench is not included, so you will need a tool for installation. The original screws are likely steel, but the advantages of titanium are its light weight, rigidity, and corrosion resistance. The disadvantage is that it is 3-4 times more expensive than steel, which is probably why manufacturers don't use it. Titanium is said to be softer than steel, but it shouldn't make much difference unless you tighten it with excessive torque.