Looking at some recent reviews, you might come to the conclusion that Thule heard all the complaints here about the end caps being shown in the picture, but not actually being in the box and rectified this problem. Some people claim to have gotten end caps. However, like me, you would be wrong in this conclusion. As of June 2015, they still don't include end caps. Maybe these people saying they got end caps got them with a foot purchase? At least in my case when I was just buying the bars to replace the rusty ones on my car, no end caps.
I was (un)fortunate enough to get these a bit cheaper from Amazon Warehouse Deals which was the main reason for opting for the top of the range bars as opposed to a cheaper alternative, however I was stung when I realised that the keys and lock barrels are missing from the box - pretty much wipes out any discount I had! Naively, I did not realise they were missing until I had proudly installed the bars on the car, so I'll just cut my losses and purchase a new set in due course... I'll probably buy the same set as the ProRide 591's that I also purchased - if only they hadn't been lost by Hermes (on behalf of Amazon) who claim to have delivered them, but that's another story.
Aluminium bars include T-track slots which allow you to use the full length of the bars for load carrying. The WingBar not only looks good but more importantly includes a device which reduces wind noise to the minimum, as well as reducing drag. Many customers leave their Thule WingBars in place from week to week, especially if they are taller vehicles and fitting is awkward.