It it turns out the spinner handle is 100% identical to the Blackhawk GW9550 , well that's another Stanley / Proto produced piece in this set..
I wouldn't be surprised if everything in this set was made by Stanley / PROTO.
Edit: the universal is a dead ringer for the GW 957A, I think this whole set probably was manufactured by Stanley / Proto.
On the outside the sockets don't match the Blackhawk GW 612m 12mm I have, but the machining on the inside definitely does.