The 1551QFLGY pairs the 40 x 40 x 15 mm 1551Q body with a lid that has mounting flanges molded in, finished in light gray (RAL 7035) ABS. Over the flanges the part measures 56.30 mm (2.22 in) long, giving two fixing points for wall mounting or a tie-wrap attachment. It suits OEM and maintenance teams housing a small PC board up to 34.5 x 34.5 mm in a neutral gray housing.

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 gray colour is specified as RAL 7035.

Outside, the 1551QFLGY measures 1.58 in x 1.58 in x 0.59 in (40 mm x 40 mm x 15 mm), with the length of 40 mm quoted not including the flange; overall length across the flanged lid is 56.30 mm [2.22 in]. Inside dimensions are 35.12 mm [1.38 in] long, 35.00 mm [1.38 in] wide and 11.00 mm [0.43 in] high. The maximum PC board size is 34.5 mm x 34.5 mm, and the shipping weight is 0.04 lbs (0.02 kg).

Each flanged assembly includes the box, the lid and 2 self-tapping #4 x 1/2" cover screws, nickel 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.