Fits some X4 Hyper 600cc Chassis. Offset 1" to get the bearing carrier closer to the sprocket carrier for tighter corner entry and greater stability. Machined from 2024 aluminum for superior strength. Rear torsion arms are measured from the center of the splined torsion bar hole to the center of the shackle mount hole. Squeeze bolt kit is included. Send us your old torsion arms or a sketch, and we will offset torsion arms to you specifications at no charge.