The 1591LBU is the blue version of the compact 1591L enclosure, measuring 3.35 x 2.2 x 1.54 in (85 x 56 x 39 mm). It is intended for product designers who want a small, coloured ABS box and lid that holds circuit boards vertically.

The 1591L drawing lists the blue 1591LBU in FR ABS, UL94 V-0, and the part page confirms a UL94 V-0 flame rating and IP54 ingress rating. Lap joint construction protects against access of dust and splashing water. Keep solvents, thread lockers and cutting fluids away from the plastic, as some chemicals can damage or weaken it.

The interior measures 78.71 mm [3.099 in] long, 51.71 mm [2.036 in] wide and 34.90 mm [1.374 in] high. Card guides molded into all side walls accept 1.5 mm (0.062") boards; the 2.09 mm [.082 in] guide slot and 29.90 mm [1.177 in] guide height are shown on the drawing.

The 1591LBU includes box, lid, 4 cover screws and pre-installed brass inserts accepting M3 - 0.5 machine screws; recommended torque is 35.5-42.5 ozf.in (25-30 cN.m). It is RoHS and REACH compliant, ships in shrink wrap at 0.14 lbs (0.06 kg), and can be factory modified by milling, drilling or printing.