We have 6 Metal Crab Pins nos.  They measure about 1 1/2" x 1 1/4" with a single pin on the back center.  I would say these date somewhere between the late 1980's - early 2000's as I purchased them straight from the mill which was closing.  They are a bright red with the pin backs in place on the back. 

6 Metal Crab pins nos