The SuperKEKB design reuses many components from KEKB.[1] Under normal operation, SuperKEKB collides electrons at 7 GeV with positrons at 4 GeV[2] (compared to KEKB at 8 GeV and 3.5 GeV respectively). The centre-of-momentum energy of the collisions is therefore at the mass of the Υ(4S) resonance (10.57 GeV/c2).[5] The accelerator will also perform short runs at energies of other Υ resonances, in order to obtain samples of other B mesons and baryons.[1] The asymmetry in the beam energy provides a relativistic Lorentz boost to the B meson particles produced in the collision. The direction of the higher-energy beam determines the 'forward' direction, and the affects the design of much of the Belle II detector.