034Motorsport 034-402-1001 Solid Rear Sway Bar
It's 2 way adjustable, solid spring steel and 25.5mm thick. They designed it specifically to work with the stock front sway bar. Everything I have purchased from 034Motorsports the far has been of superb quality and I expect that to continue to hold true.
Why a beefier rear sway bar? Audi's like to understeer, a lot. Increasing rear sway bar stiffness is a great way to counteract understeer, increasing rotation at the rear of the car and potentially even generating lift off oversteer in front and all-wheel drive vehicles. My goal is for more neutral handling.