  We present a Resonant Switch (RS) model of twin peak high-frequency
quasi-periodic oscillations (HF QPOs), assuming switch of twin oscillations at
a resonant point, where frequencies of the upper and lower oscillations $\nu_U$
and $\nu_L$ become to be commensurable and the twin oscillations change from
one pair of the oscillating modes (corresponding to a specific model of HF
QPOs) to some other pair due to non-linear resonant phenomena. The RS model
enables to determine range of allowed values of spin $a$ and mass $M$ of the
neutron star located at the atoll source 4U 1636-53 where two resonant points
are observed at frequency ratios $\nu_U:\nu_L$ = 3:2, 5:4.
