The 1591USBK is the black economy version of the square 120 x 120 x 59 mm (4.72 x 4.72 x 2.32 in) 1591 Series enclosure, without mounting flanges. It gives builders and OEMs a spacious, low-profile project box where flame retardancy is not required.

It is molded from general purpose ABS rated UL94 HB; economy versions are not flame retardant. Card guides molded into all side walls hold 1.5 mm (0.062") boards vertically, and lap joint construction protects against dust and splashing water to an IP54 design.

The drawing gives 120.00 x 120.00 x 59.00 mm overall and 113.54 x 113.54 x 54.90 mm inside. Four #4 self-tapping screws fix the lid into fully plastic posts, and black enclosures include black screws; recommended torque is 42–57 ozf.in (30–40 cN.m).

The 1591USBK includes box, lid and 4 cover screws, ships in shrink wrap at 0.32 lbs (0.15 kg) and is RoHS and REACH compliant. The 1591UC clear lid and 1591TS100BK replacement screws are listed accessories.

The drawing notes that the enclosure can be factory modified with milling, drilling or printing, and solid models are available in .stp or .x_t for design work. 1591Z card adaptors allow horizontal PCB mounting.