these are found under several brands and likely made by imperial. mine are in a blue point roll but i think most every brand has carried sold them in a similar fashion, just a made in usa stamp and the size on the handle.
these are 3/8-5/8 and split open on the end to go around any hex shaped fastener. they don't work in every application but they do work and work well. i use the 9/16 most. not on a flare nut but to turn a long hex shaft on my planter. the shaft is about 20 feet long and i can open it up and slip it over the shaft in any location.