Originally Posted by
JohnDThompson
The Duopar is a great derailleur; I have several on bikes here. My commuter bike has an original 1978 "Eco" (steel) version I've been using continuously since I bought it new.
Looking at the pictures in the link you provided, I suspect that the unit on offer is actually an "Eco" model. All the titanium ones I've seen (including several I have here) have dark titanium bodies and cages, while the Eco models have the lighter steel bodies and cages.
Titanium on the top row, steel on the bottom row:
You can also see the bluish tinge to the arms on the Ti ones.