The upgrade of the PETRA II storage ring to PETRA III required the total rebuilding of one-eighth of the ring to provide the electron-beam optics for eight straight sections, each offering space for one 5 m long or two 2 m long insertion devices - so-called "undulator" magnets. 14 beamlines with independently tunable insertion devices are available. The electron energy is 6 GeV, with a beam current of 100 mA.
PETRA III offers a horizontal emittance of 1.3 nmrad which is a so far unrivaled value for 3rd generation synchrotron radiation sources operated at a comparable high particle energy for the production of hard X-rays.