"Explorer" brand owned by Guttman, one of if not the first US knife company to contract in Seki Japan. They imported a whole bunch of models under the Explorer and Edge Mark brands including various daggers and hollow handled "survival knives". The 440 stainless is most likely Aus6, as many US companies back then used the US equivalent for customer familiarity rather than the Japanese designation. Very similar models were made in the early 1980s for brands Jim Parker, possibly Jim Frost, Valor Corp, etc. Many of these were basically copies of the then popular Gerber models.
This boot knife is used, has been sharpened but is perfect to carry, use and would be comforting in a pants or cargo pocket. The stainless steel sharpens and cuts well.
It has a reassuring feel.
to view 8 Vintage folding knives got to:9 Vintage Folding Knives for Sale
OAL opened 8", 3.5" blade, 4 3/4" closed AUS 6 steel. micarta handles,