The 1551USB3BK is the largest of the three 1551USB sizes, a 65 x 30 mm housing with an opening for a male USB-A connector. Molded in black ABS plastic, it is intended for dongles and small printed circuit boards fitted with a male USB-A connector, making it a practical choice for OEM engineers and product designers packaging compact USB devices.

The body measures 2.56 in x 1.18 in x 0.61 in (65 mm x 30 mm x 15 mm) per the part page, with the drawing showing 65.00 mm x 30.00 mm and an overall height of 15.50 mm [0.61 in]; the series ordering table lists the depth as 0.63 in (16 mm). The part page gives a maximum P.C. board length of 25.5 mm and width of 59 mm. The satin-textured cover is recessed 0.50 mm for easy label installation.

Each purchased assembly includes the box, lid and two #2 x 1/2" self-tapping cover screws, with a recommended torque of 35-43 ozf.in (25-30 cN.m). The black finish is listed on the drawing as RAL 9011. Per the series notes, black boxes ship with matching black self-tapping lid screws. Molded-in mounting posts accept #2 x 3/16" self-tapping screws for the board; these are not included and are available as 1553WTS100 (pack of 100). The USB connector itself is not included.

The enclosure is designed to meet IP51, carries a UL94-HB flammability rating, and is RoHS and REACH compliant. It ships in a bag at 0.03 lbs (0.01 kg). The drawing notes a recommended PCB thickness of 1.50 mm [0.06 in], which can be thicker, and states the USB connector must be attached to the face of the PCB in the orientation shown so varying board thickness will not shift the connector within the USB opening. Some chemicals can damage or weaken ABS, including acetone, thread-locking compounds and cutting or tapping fluids, so check compatibility before use. Factory modification (milling, drilling, printing) is available, and solid models are offered in .stp or .x_t.