The 1551KRBK is a black ABS plastic miniature hand held enclosure fitted with a key ring kit, built on the 1551K body (the manufacturer lists it as "1551KBK with key ring"). It suits OEM engineers and electronics designers who need a pocket-sized housing for a small printed circuit board, such as a key fob style remote, tag or tester, or who want a compact potting box.

The box and lid are molded from general purpose ABS plastic in black (RAL 9011) with a UL94 HB flame rating. A lap joint between box and lid gives protection against dust and splashing water, and the enclosure is designed to meet IP54. Walls are 2 mm (0.08 in) thick, and the enclosure is predrilled in the narrow side for the key ring.

Outside, it measures 80 x 40 x 20 mm (3.15 x 1.57 x 0.79 in) with the lid in place. Inside you get 74.73 mm length, 34.73 mm width and 16.00 mm height, and the drawing gives a maximum PC board size of 74.00 x 34.00 mm. PC board standoffs are molded into the interior and accept #2 self-tapping screws (not included).

Each purchased assembly includes the box, lid and 2 black plated #4 x 1/2 in self-tapping cover screws; recommended torque is 35-43 ozf.in (25-30 cN.m). The part is RoHS and REACH compliant, ships in a bag at 0.06 lbs (0.03 kg), and a matching grey version is available as 1551KRGY.