The Rack Rails are designed to support rack mountable equipment at any width, such as servers, patch panels, or other networking equipment . They come in pairs and are easily attached to your desk or wooden frame. NO NEED TO THREAD SPECIALLY: The triangle self-tapping screws can automatically tap the internal thread in one step when fixing your equipment onto the rails, as the vedio. Available in a variety of sizes. Cold rolled steel with black powder coating and rack unit is separated by gap on rails. 8U Size. Including: 2 x Vertical Rack Rails 4 x M5 Self-propelled Screws 32 x Screws for Installing Equipments onto this Rack rails.