HPI Firestorm trucks. In addition to the added durability, these 0 degree hubs allow the adjustment of the rear roll center of the truck using the included ball studs and spacers. The wheelbase is also adjustable using the included spacers. They’re laser etched to help identify the left and right blocks as well as the degree setting. Complete instructions are included.

Small Cross Wrench, 2mm Hex Wrench and Diff Grease