The MPB12 is the largest enclosure in the MPB Series of Type 12 mild steel miniature pushbutton enclosures, with twelve holes for 22mm miniature oil tight pushbuttons, switches and pilot lights. Finished in ANSI 61 gray, it protects its devices from dirt, dust, oil and water and gives space for a comprehensive operator station. The RAL7035 light gray version is the MPB12LG.

The MPB12 has an internally hinged removable cover designed to hold the cover open during wiring. It is formed 16 gauge steel with smooth continuously welded seams and welded brackets for enclosure mounting. Captive cover screws thread into sealed wells, an oil resistant gasket and adhesive seal the cover, and a bonding stud on the door plus grounding stud on the enclosure are provided. Cover and enclosure are phosphatized and powder coated ANSI 61 gray.

The enclosure is 10.38 in (264 mm) high by 6.50 in (165 mm) wide by 4.25 in (108 mm) deep. Its drawing shows 11.38 in overall height, a 10.69 x 6.81 in door, a 9.38 x 5.46 in door opening and 4.29 in inside depth. The 0.89 in pushbutton holes are spaced 1.88 in vertically and 1.50 in horizontally, and 0.25 in mounting holes are on 10.88 x 5.63 in spacing.

The series is rated UL 508A Type 12 and 13 and CSA Type 12 and 13, and complies with NEMA Type 12 and 13 and IEC 60529 IP54; appropriate components are required to maintain these standards. It carries UL File # E65324 and CSA Cert. # LR21001, is REACH and RoHS compliant, and ships boxed at 6 lb (2.72 kg).