Avid B44.2 aluminium centre cap
Avid’s new B44.2 aluminium centre cap is a fresh take on the design which keeps your chassis secure and makes the car easier to work on. The design eliminates 4 screws for the original cap and instead directly links the front and rear upper decks with taper mounts that key into the upper decks. The added benefit of this design is that maintenance is simplified, when you only remove 4 screws and the entire upper deck assembly is loose for easy slipper clutch removal.
Source: Avid [avidrc.com]