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fkwIm not an expert but the factory number (6), location (Ohio), and year (1910) on the box and taxstamp matches the Polar Bear cards exactly. Polar bear cards have 350 and 460 series cards But thats as much as I know.
Usually on unopened eBay packs something doesnt match up.
And yes Id open it. 
But I also would never pay more than what an EX/NRMT T206 card sells for.
PS. A Polar Bear pack recently opened at a National Convention (in NY) was rumored to have 5 cards in it (page 41 issue #3 "Old Cardboard").