I think I have an Adam with the same bow treatment and some Englsih manufacturers used it as well. Looks easy enough until I tried to make one myself.Dobbs and Knox used to do it on their fedoras, and Stetson to a lesser extent. I first really noticed it, though, on Gannon hats commissioned by @moontheloon and @Frunobulax. It quickly became a favorite bow treatment of mine and now sits astride 2 customs... this natural Gannon and my custom natural from Black Sheep Hat Works.