This gear set is precision made using injection molded POM (Polyoxymethylene aka Delrin or Acetal).
POM is the perfect material for gears as it has high mechanical strength and rigidity, toughness and high resistance to repeated impacts and long-term fatigue endurance. It also has excellent resistance to moisture, gasoline, solvents, and many other neutral chemicals.
Bottom line is that this is the right material for gears over what other makers are using such as Nylon or ABS plastic. Not to mention these are super quiet.
The set comes with the following:
52,53 and 54 tooth spur gears
9,10,11 and 12 tooth pinions
This set is compatible with PN Racing's ball differentials (upgrade to 48 pitch MR2048, replacement for 64 pitch diffs: MR2050, MR2049 and F1005) and an upgrade to Kyosho's adjustable ball differential MZW436.
While we haven't verified, it should also fit GL Racing's GLR-006 & GLF-S-017 with the addition of a radial bearing. The gears may fit other manufacturer's differentials as well.