SpeedTek RC hardened stainless steel spool only! (includes 2 bearings) fits in the Arrma 6S Models including Limitless V1 and Infraction V2 !  Does not fit in the V2 Limitless. The center driveshafts are the incorrect length.
 
We use these spools on all of or drag racing & speed run vehicles. 
 
The high speed spool comes with a 8mm hardened stainless steel spool and hybrid shielded bearings (2).