The "K" Style Flanges from The King of Jeeps

I purchased a 1957 Berg's Truck and Parts Co (Aka the King of Jeeps) Catalog off of eBay. It included this flyer for a set of hubs I've never seen. Anyone ever run across these? (You can compare them to other flanges/summer hubs here: http://www.ewillys.com/2017/01/09/warns-summer-hubs/)