Tek screws / self drillers / self tappers
Tek screws, also known as self drillers or self-drilling screws or self tappers, or self-tapping screws are a special type of screw that can be used on metal fence components without drilling a pilot hole.
The reason these screws can be used on metal without first drilling a hole is that they are designed to have a tip that acts like a drill bit as they're being screwed in place. This small section of drill bit creates the hole for the screw as it turns. This makes this type of screw very convenient for fence projects and tasks that require on-site installation of some elements.
Tek screws or self-drilling screws come in a huge variety of finishes and materials, different lengths and diameters, and with different types of heads. So there's sure to be an option that will work for your fence project.