There is no good reason for those mounts to have sold for such a high price. I'm pretty sure they were private labeled Weaver swing overs as both brands look much the same. The peep sight is not all that uncommon, just not often found on that particular base. In my best "Antiques Roadshow", I'd say those swing overs were worth about 25-bucks at auction! The sale is either a bunch of nonsense or the seller made the "deal of the century"
