A screw is used to fasten paarts together with a nut, a standoff or directly into a threaded receptacle. We have here a pack-of-4 nickel plated screw with Philips hex cap. The thread size is M5, it fits other M5 screws/standoffs. The thread length is 10 mm. These screws come with attached washers. You can use an M5 hex wrench or a Philips screw driver to turn the screw.