Abstract: A recreational vehicle including a “slide-out” cabin portion is equipped with a locking mechanism which comprises a lock door pivotally rotatable to interfere with the wall opening periphery through which the slide-out cabin portion transitions. The slide-out further has an extensible portion front end positioned external to the wall opening such that the dimensions of the extensible portion front end exceed the dimensions of the wall opening. The extensible portion front end contacts the main cabin wall opening periphery along the entire perimeter of the wall opening thus completely sealing the wall opening when the slide-out is in a fully retracted position. Further, the slide-out locks are positioned sufficiently close to the extensible portion front end that when the slide-out is in a retracted position and the slide-out locks are in the locked position, the main cabin wall periphery is pinched between the slide-out locks and the extensible portion front end.