Overview: ll of these strengthening upgrades, combined with some of the best engineering grade nylons in the industry equate to a set of ultra lightweight replacement A-arms that have unmatched durability and performance. Place your trust in American made. Trust RPM. Features: The inner hinge pin bosses are roughly 20% thicker than stock (and dramatically thicker than first gen Losi A-arms). We've increased the overall thickness of the A-arm by roughly another 25%. Support beams are consistent on thickness and are roughly 50% thicker than some of the thinner stock supports. Unique shock surround protects the lower shock bottom. It's less prone to damage since the shock pivot ball is captured and no longer fully exposed.