BOX3-1455N-BK Black Aluminum Box, For 3U Sized PCBs, With 11 Card Guide Slots, Box = 6.30 x 4.06 x 2.10 in Box is anodized black silver extruded aluminum with metal end plates and polycarbonate plastic bezel. Box Size 6.30 x 4.06 x 2.09 inches (160 x 103 x 53 mm) 11 built-in card guides for 3U sized PCBs (100 x 160mm). Side out top panel plate. Rugged body constructed from extruded aluminum with a minimum thickness of .06 (1.5 mm).