We provide a simple extension of Bolthausens Morita type proof cite{Bolt2} of the replica symmetric formula for the Sherrington-Kirkpatrick (SK) model and prove the replica symmetry for all $(beta,h)$ that satisfy $beta^2 E, text{sech}^2(betasqrt{q}Z+h) leq 1$, where $q = Etanh^2(betasqrt{q}Z+h)$. Compared to cite{Bolt2}, the key of the argument is to apply the conditional second moment method to a suitably reduced partition function.
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