These were the style of hangers used on some of the finest constructeur bikes. You'll see them on bikes by Singer, Toei, Routens, Alp, Reyhand, Goeland, etc. And they were often made by the constructeur. It's one of those little details that defined constructeurs; they made more than just the frame. Add a little retro elegance to your Randonneur.
Sold as a single unit.