McLaren continues to use the end of the 2016 season as an extended pre-season test session, with the front brake duct an intense area of focus for them in the last few races.
Both drivers have the newest configuration installed on their MP4-31 in Abu Dhabi, with Fernando Alonso successfully running it in Brazil last time out.
The entire assembly is a departure from the direction the team has been pursuing the rest of the season and has more to do with the incoming regulations than the 2016 ones.
We covered the changes in more detail at the last GP but in short the blown axle that previously marginalised the wake created by the front tyre has been blanked off, whilst the drum's role in pushing airflow out through the wheel face has been increased to compensate, with a much larger crossover pipe being employed.
You'll note that in Abu Dhabi the crossover pipework has had a blanking panel added, which changes how the heat created inside the drum radiates into the wheel rim that sits in close proximity.
Various numbered sensors can seen on the surface of the drum that measure the conditions that are present and give the engineers further insight into how their changes have had an effect.