Shimano FC-R550 Double Crankset. 130 bcd. 172.5mm arm length. 53/39 Chainrings.  Alloy construction. This came off a bike from around 2010, with very low mileage apparent on bike or components.  It is considered Shimano 105 quality.  Reviews say that it has very nice shifting, due to stiff outer ring, ramped and pinned rings.  Teeth on chainrings are still sharp and undamaged, with lots of miles left.  Minor scratches on outside, very shinney & bright appearance, Shimano graphics are excellent.  I believe this is what is called Hollowtech II.