The 1591ABU is a blue ABS plastic enclosure in the 100 x 50 x 25 mm 1591A size. The colour makes it a good choice when a product needs to stand out or be colour-coded, while keeping the 1591 series' molded card guides for vertical printed circuit board mounting.

Outside it measures 3.94 x 1.97 x 0.98 in (100 x 50 x 25 mm). The drawing lists inside dimensions of about 93.83 mm long, 43.83 mm wide and 20.90 mm high. Card guides molded into all side walls accept 1.5 mm (0.062") boards, and the 1591Z card adaptors (6, 50 or 100 per pack) allow horizontal board mounting.

The material is ABS plastic with a UL94 V-0 flame rating; the drawing lists the 1591A blue colour under flame retardant ABS. The purchased assembly includes box, lid, four cover screws and pre-installed brass inserts that accept M3 - 0.5 machine screws. This part's drawing gives a recommended torque of 42-57 ozf.in (30-40 cN.m). Lap joint construction protects against dust and splashing water, and the enclosure carries an IP54 rating.

Optional accessories are the 1591AC clear polycarbonate lid, the 1599CLIP nylon belt/pocket clip and 100-packs of plated M3 - 0.5 x 10 mm cover screws (1591MS100 silver, 1591MS100BK black). It is RoHS and REACH compliant, ships shrink wrapped, and has a shipping weight of 0.11 lbs (0.05 kg).