mid century vintage industrial control fuse box with latching steel door and four, edison screw base, sockets.
This heavy steel box was made by The Clark Controller Company of Cleveland, Ohio - American Switch Division. It still has the original wiring diagram on the inside of the door. It's rated for 30 amps and 125-250 volts.
It measures about 9 3/8" x 7 3/8 x 2 3/4" overall and 6 3/4" x 5" over the door. It has wear and scraping to the old gray paint and the smaller knock out slugs (the holes are about 13/16" across) have been knocked out on all 3 positions on the top and the bottom as well as the center position on the left hand side.