Joined: Jan 2010
Posts: 9,797
Likes: 1,763
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
I'm pretty sure that it's one of SR's cold-forged stems, a model or two before their equally hi-end FX quill stems appeared.
It's an extremely popular design, Ambrosio offered a similar style and many others did as well.
My Miyata Six-Ten came with what I believe is SR's melt-forged equivalent of this one, the SR Custom, perhaps the most mass-produced stem ever(?).