Kyosho Optima ball differential kit
Kyosho have introduced the optional ball differential kit for the re-release Optima 1/10th scale 4WD buggy. Designed for the use in belt-drive configuration the set includes all needed parts to build one rear differential but it is understood that the diff can also be run in the front of the buggy. Using the unit can improve handling both on slippery and also high-grip tracks and included with the set come all needed parts including suitable greases.
Source: Kyosho [kyoshoamerica.com]