I use this truss rod key mainly for adjusting truss rods. However, being a bit of a loose canon, I have also used it to adjust other things including various screws and two-force members. While the description says that this is a key please be warned that the implement is less effective in this role. For example, when I lost the keys to a hire car recently it was the first thing I reached for. However, I found I had to hit it with a hammer to get it to fit into the door lock and also use a large pair of pliers in order to apply sufficient rotational force to satisfactorily engage the lock. A hammer and pliers are not provided with this product - you will need to order these from somewhere else. Moreover I would also suggest that you take out the full damage waiver at the point of hiring the car. While I cannot fault the product under normal use, my enthusiasm has been somewhat dampened because I have had to sell my guitar to meet the costs of returning the hire car to its original condition.