The 1551RBK is a 50 x 50 x 20 mm (1.97 x 1.97 x 0.79 in) black ABS enclosure from the 1551 miniature series. Its 20 mm depth gives an inside height of 15.98 mm (0.63 in), leaving more room for taller components than the 15 mm deep 1551S of the same footprint. It accepts a PC board up to 44 x 44 mm and suits OEM electronics, sensor nodes and potted assemblies.

The body is molded from general purpose ABS plastic with 2 mm (0.08 in) walls and carries a UL94 HB flame rating. Lap joint construction between box and lid protects against dust and splashing water, and the enclosure is designed to meet IP54. PC board mounting bosses are molded into the interior and accept #2 self-tapping screws. The black colour is specified as RAL 9011.

Outside, the 1551RBK measures 1.97 in x 1.97 in x 0.79 in (50 mm x 50 mm x 20 mm). Inside dimensions are 44.72 mm [1.76 in] long, 44.72 mm [1.76 in] wide and 15.98 mm [0.63 in] high. The maximum PC board size is 44 mm x 44 mm, and the shipping weight is 0.04 lbs (0.02 kg).

Each assembly includes the box, the lid and 2 self-tapping #4 x 1/2" cover screws, black plated to match the enclosure; the recommended torque is 35-43 ozf.in (25-30 cN.m). Screws for securing the PC board are not included; the drawing lists part 1551ATS100 (#2 x 3/16" self-tapping (4.8 mm), pack of 100). The part is RoHS and REACH compliant and ships in a bag.

Hammond notes that some chemicals can damage or weaken ABS, including acetone, ketones, thread-locking compounds and cutting or tapping fluids, so check compatibility before cleaning or modifying. The enclosure can be factory modified (milling, drilling, printing) and solid models are available in .stp or .x_t format.