The MPB4 is the four-hole, single-column model in the MPB Series of Type 12 mild steel miniature pushbutton enclosures, finished in ANSI 61 gray. It accepts four 22mm miniature oil tight pushbuttons, switches or pilot lights and protects them from dirt, dust, oil and water, suiting slim control stations. Its RAL7035 light gray counterpart is the MPB4LG.

The enclosure is formed 16 gauge steel with smooth continuously welded seams and welded brackets for mounting. Captive cover screws thread into sealed wells and the cover seals against an oil resistant gasket and adhesive. A bonding stud is provided on the door and a grounding stud on the enclosure. Cover and enclosure are phosphatized and powder coated ANSI 61 gray; the MPB4 cover is not hinged.

The MPB4 measures 8.88 in (226 mm) high by 2.75 in (70 mm) wide by 3.50 in (89 mm) deep. Its drawing shows 9.88 in overall height, a 9.19 x 3.06 in door, a 7.50 x 1.32 in door opening and 3.54 in inside depth. The 0.89 in pushbutton holes sit on 1.88 in spacing, and the 0.25 in mounting holes are on 9.38 x 1.88 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 3.38 lb (1.53 kg).