Clamping Rackshelve for the S-4000M Merge Unit For components which require captivation, our RC and CAP series clamping rackshelves offer an economical and highly functional solution. Equipped with rubber-lined clamps which secure your component from the top, all RC and CAP series products are additionally outfitted with adjustable “L” brackets in back to provide an optimally secure fit. Vented bottoms offer superior cooling, while a robust 16-gauge steel design maintains structural integrity even on the road.