Precision mass measurements of n-rich nuclei from N=50 to N=82, J. Äystö, Department of Physics, University of Jyvaskyla, Jyvaskyla, Finland − Our knowledge of binding energies of neutron-rich nuclei has experienced a major revision during the last five years due to the introduction of Penning-trap based mass measurements. As an example, new mass values for nearly 300 nuclides produced in fission with  uncertainties of 10 keV or less have become available. The data produced at three Penning trap facilities at Jyvaskyla, CERN-ISOLDE and Argonne cover all isotopic chains from Ni to Pr, except iodine. In this talk the data is reviewed and discussed using the mass differentials such as neutron and two-neutron binding energy as well as odd-even staggering of masses to probe the strength of the N=50 and N=82 shell gaps and associated pairing effects.