Two distinct relations between QPO frequency f (Low & High frequencies) and ´black hole´ mass M have been established by observation (Smith et al, 2018). M∙f = const with different constants for the L and H relation. The ´black hole´ attributed QPOs agree at high frequencies with the spin frequency of the most rapidly rotating neutron stars of the two classes of ´ordinary´ pulsars and the ms-pulsars. ´Ordinary´ pulsars fit the L-f relation and the ms-pulsars follow the H-f relation, permitting some calculation of their neutron star mass. This is illustrated for the Crab pulsar (´ordinary´) and the ms-pulsar J1748-244ad. This observation which suggests a physical link between the spin frequency of extremely rotating neutron stars and QPO frequencies of ´black holes´ is likely to be a consequence of the ´Aschenbach´ effect, being effective at Kerr parameters of a>0.9953 (Aschenbach, 2004).