Hammond ADSU Solid & ADSV Ventilated Depth Adjustable Shelves – Black – Hammond ADSV1825BK, This cleverly designed shelf from Hammond has a telescoping design that provides three convenient usable depths. It fits within a single EIA rack unit and can telescope to cover the entire depth. Hammond ADSV1825BK 1U Depth Adj Shelf 457mm-635mm Vented Black