This is an optional wheel hex hub adaptor. Aside from the great looks, aluminum alloy will not flex as much as plastic under stress or during high ambient temperatures.
Specification:
Compatible with:
brand name: RedCat, item number: RER09587, RER09588, RER09585, RER09586, model: 1/10 Everest Gen7 Pro and 1/10 Everest Gen7 Sport