I keep a bottle jack in my little trailers box. I put a bottle jack in the truck when I use the car trailer. I have a tool set I keep in the truck that I could use change the flat. Something else that is good to carry with a car trailer is blocks to put underneath the back of the trailer to keep from picking the truck up off the ground.
It would be easier to tell what is right with the box. The biggest issue is the lid. It has a 1/4'' gap on one side and over 1'' on the other, it does not seal. At first I thought they did not have it centered but the lid is just made wrong. Some of the rivets that hold the hinge on are loose. Nothing is square on the box. You can lay a angle finder on the side of the box and move it to the lid and they are different. The handle that opens the box is crooked. There is paint or powdercoat chipped is off the lid in a couple of places. Both sides of the box have bulges in them. If I put it on my trailer everyone would think got the trucks bumper into the box and messed it up. Worst of all the box has a big decal on the inside of the lid that says "Proudly made in the USA". If they would have used some pride when they built the box it would be a nice box. I sat it on the trailer and it fit the trailer nicely. It is a shame it is not constructed properly.