RPM Oversized Front Spindle Blocks for the ECX Boost, Circuit 2WD, Racket 2WD and Torment 2WD are developed to enhance performance and durability of yuor ECX automobile. RPM Oversized Front Spindle Blocks bump up the bearing size to 5x11x4mm bearings (not included), nearly doubling all load and tiredness scores over the stock bearing size! That indicates much better performance, longer life and more time between upkeep durations. Each set of RPM spindle obstructs is molded from their ultra-durable nylons refined to keep you rolling when everything else would have fallen apart. These parts keep all stock geometry for a direct, no issues swap and are backed by RPM's restricted lifetime warranty versus breakage.