A crowfoot socket wrench is used the same way an ordinary socket wrench is, but it is not cylindrical. The head is open-ended to allow flexibility in tight spots where you can't completely rotate a socket wrench. These are excellent for car repairs, especially work done underneath the vehicle, or under the hood where there are many tight fits. The one universal problem with using the crowfoot under the hood is that it's easy to drop the wrench as you try to navigate tight spaces. It's helpful to attach a lanyard to the wrench and wear it around your wrist. If you lose your grip, you can simply pull your arm out of the tight spot, and re-grip.