Avid MBX8R carbon arm inserts
Avid’s new MBX8R carbon arm inserts set includes the 1.0mm front and rear inserts to offer your buggy another great tuning feature by reducing the flex and twist in the arm. In the past, Avid offered several different thicknesses but have learned that 1.0mm is all you need so no more guessing. These are available as a complete set or individually.
Source: Avid [avidrc.com]