I have seen two types. The one shown in John G's link ( with and without a key ) and an open knife switch type.
They can be bought at any auto parts store or I think I saw them at Harbor Freight.
The custom cars show guys use them as a safety factor. When they drive baby to a show, the switch is a quick, easy way to disconnect the battery while the car or jeep in your case is on display. They hide them where they can get to them but not obvious to an on looker.
Keeps some body from doing something they shouldn't ( Not that anyone would do that
), like accidently hitting the starter or starting the car or jeep and hitting people and other cars around them.
I would used the enclosed one in your case. Less likely to have something fall on it and short out.
Hint: they work on the ground side as well as the B+ side of the battery.