Are you ply lining your van? 
Are you building a campervan?
Please note that I have other listings that have larger quantities which are cheaper and include free delivery
For Van / Campervan Plywood Lining Brackets Ply Lining fixings.  Also known as Van boarding block/bracket.
If so then some parts of the van are too thin to screw.  For this you will require these brackets to install panels over the rear doors and side door, usually where a window would usually sit as that's the thinner parts of the van.  These brackets allow you screw downwards in to the wider panels which will hold the plywood in place.