Vanished Tool Makers: G.M. Co. Manufacturing Inc., Long Island City, New York

Below, a couple of "Unbreakable" brand clamps:

The smaller clamp is stamped "G.M. Co."

Below, a stamped metal square made by the same firm:

This company is not, as you would suspect, General Motors, but a manufacturer that made a variety of tools, as shown in the 1951 Popular Mechanics ad below, and in the pics below it.  That's the extent of the information I can unearth on the company.

The Family Handyman, May 1955

Below, some pictures considerately sent in by a visitor who notes, "these are examples of the small 1/4” square drive socket sets that G.M cranked out by the millions (my best guess based upon how frequently I see them on Ebay.):"  Many thanks for these images!

Note the unusual button for selecting the direction in which the drive turns:

Other offerings pictured on the web:

Update; the "Unbreakable" name also appeared on a multitool made by the company. Thanks Ski!

ebay 353163787069 01

Update Sept/2023

Below an all-purpose saw from the company, showing a different logo; thanks, James! Hope you could find a new blade to keep it useful.