When you work in a confined space, such as under the hood, some nuts and bolts are very difficult to reach. Since it is simply physically impossible to reach the fasteners with your hand and wrench, an extension cord is helpful in this situation. The big plus of the extension cord is that it is flexible, and this further increases your chances of getting access to the necessary node. Of course, you won't be able to tear off any powerful nuts with this extension, but it's very convenient to tighten small bolts. The seller offers 6 sizes of extensions for different heads and ratchets.