Energy spectra of delayed neutrons from the mass-separated fission products 79(Zn, Ga), 80, 81Ga, 94, 95Rb, and 129, 130 In have been measured. The neutron envelopes are deduced and compared to predicted envelopes using various mass formulas. The agreement is good for all precursors except for 79(Zn, Ga), whose predicted neutron window is too narrow to reproduce the experimental results.