If you have the small sofa slide like my 28 BHS, you open the cabinet over the sofa and it goes between the trailer inner wall and the top of the slide, inside the hole in the top of the opened cabinet. It has to be tightened by turning by hand to lock it tight between the wall and the slide. I`m surprised they never used it as the slide can move in and out at the top quite a bit without the lock in place.
2004 Chevy 2500HD Crew Cab 6.0l, 4.10r
2010 Jayco Jayflight 28BHS
Reese Strait Line with Dual Cam
P3 Brk controller