The 1591SBK is a black flame retardant ABS plastic enclosure from the 1591S size of the 1591 Series multipurpose project boxes with card guides. Measuring 4.33 x 3.24 x 1.73 in (110 x 82 x 44 mm), it gives electronics designers, OEM engineers and hobbyists a compact housing for printed circuit boards that stand vertically in molded guides. It appears in the series ordering table under Flame Retardant ABS Enclosures without mounting flanges, with a nominal size of 4.33 x 3.23 x 1.73 in.

The box is molded from easy-to-machine flame retardant ABS carrying a UL94 V-0 flammability rating. Lap joint construction between box and lid protects against dust and splashing water, and the enclosure is designed to meet IP54. Because it is a black enclosure, it ships with black lid screws.

Inside, the usable space is 103.77 x 75.87 x 39.90 mm (4.085 x 2.987 x 1.571 in). Card guides are molded into all side walls and accept 1.5 mm (0.062 in) thick boards, with a guide height of 34.90 mm (1.374 in). For horizontal board mounting, 1591Z card adaptors are sold separately in packs of 6, 50 or 100.

The lid fastens with four M3 x 10 mm Phillips machine screws that thread into pre-installed brass inserts, so it can be opened and closed repeatedly; the recommended torque is 35.5-42.5 ozf.in (25-30 cN.m). The purchased assembly includes box, lid, 4 cover screws and the brass inserts. A clear polycarbonate replacement lid, 1591SC, is available, and the part is RoHS and REACH compliant with a shipping weight of 0.23 lbs (0.10 kg).