The 1591TBG is a beige flame retardant ABS plastic enclosure from the 1591T size of the 1591 Series multipurpose project boxes with card guides. Measuring 4.72 x 3.16 x 2.32 in (120 x 80 x 59 mm), it gives electronics designers, OEM engineers and hobbyists a compact housing for printed circuit boards that stand vertically in molded guides.

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. The 1591T drawing lists 1591TBG as the beige colour of the FR ABS UL94-V0 version.

Inside, the usable space is 113.54 x 73.74 x 54.80 mm (4.470 x 2.903 x 2.157 in). Card guides are molded into all side walls and accept 1.5 mm (0.062 in) thick boards, with a guide height of 49.80 mm (1.961 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, 1591TC, is available, and the part is RoHS and REACH compliant with a shipping weight of 0.29 lbs (0.13 kg).