Diamond Calk Horsehoe Company
These pliers are stamped with Patent # 2677982. The patent was awarded May 11, 1954 and originally assigned to the American Hardware Corp. The handle spread limiter ring is stamped "Pat Pend."
This pair were made early 1973 as evidenced by the 1 in groove near jaws and pat. pend. referring to patent 3739664
The significance of the 1 means that it is the 1st die used after 1972 for that tool.
Construction grade for cutting nails and or wire.