HPI locked diffs give more traction for rock crawling than the stock open diffs. They’re direct bolt-in parts built to factory specifications for a perfect fit. Each package contains two lockers, enough to convert the front and rear diffs.
haven't used them yet but I can definitely see why I wanted them. I could have gotten out of some driving trouble if I put them in earlier.
diff lockers=now able to flip the truck back on all four wheels when overturned on it's side. Trade off is a much wider turning radius.