This unit is designed to encase the exposed bolt head so that you cannot get a wrench on it. It works. I purchased this to install over the top of one bolt head for my winch installation. It worked however, it was a tight squeeze getting the key out. But that was due to my situation and not the product design. The only concern I had is that I was not able to use a lock washer under the bolt head inside this box. That made the bolt head to high to engage the lock.

Since my Jeep is also my daily driver, and since I don't work in what some would call the most crime free area, I put these things on everything. The piece of mind of knowing your bumper/winch/jack/etc is going to be there when you get off work is worth every penny. I purchased three to start, and they were back ordered so it took a very long time to get to my house, but once they did I was quite impressed. They are pretty heavy duty, and have a door on each lock to keep out the grime. Two of the boxes I ordered used the same key, the third was different. My only suggestion is for a deeper version of this locker for the really long bolts on my bumper. However, I was able to just throw an extra washer between the lock box and my bumper and it works fine. Great product.