The 1551NTBU is a shallow, square 35 x 35 x 15 mm enclosure molded in translucent blue general purpose ABS plastic. It is meant for mounting tiny printed circuit boards or for potting small assemblies, with a translucent blue finish as an alternative to black or grey.

The enclosure uses a two-part box and lid joined by a lap joint, which protects against dust and splashing water; the design is intended to meet IP54. The plastic is UL94 HB flame rated and the walls are 2 mm (0.08 in) thick.

Outside, the 1551NTBU measures 1.38 x 1.38 x 0.59 in (35 x 35 x 15 mm) including the lid. Inside it provides 30.17 x 30.17 mm and 11.00 mm of height, with space for a P.C. board up to 29 x 29 mm. Molded standoffs accept #2 x 3/16 in self-tapping screws, available as 1551ATS100 but not included.

The kit includes box, lid and 2 black plated #4 x 1/2 in self-tapping cover screws, the finish used with blue enclosures. Recommended torque is 35-43 ozf.in (25-30 cN.m). It is RoHS and REACH compliant and ships in a bag at 0.04 lbs (0.02 kg).