Fig. 64 at the left shows a Mossberg No. 210 1/4x5/16 open-end wrench of stamped steel construction, marked with the M-Diamond logo.
The overall length is 3.2 inches, and the finish is plain steel.
This wrench was acquired as part of a Mossberg No. 14 Socket Set shown in an earlier figure.
From The Wrenching News- http://home.comcast.net/~alloy-artifacts/frank-mossberg-company.html (http://home.comcast.net/~alloy-artifacts/frank-mossberg-company.html)