Product Space is Completely Hausdorff iff Factor Spaces are Completely Hausdorff

Theorem
Let $\mathbb S = \left\{{\left({S_\alpha, \tau_\alpha}\right)}\right\}$ be a set of topological spaces for $\alpha$ in some indexing set $I$.

Let $\displaystyle T = \left({S, \tau}\right) = \prod \left({S_\alpha, \tau_\alpha}\right)$ be the product space of $\mathbb S$.

Then $T$ is a $T_{2 \frac 1 2}$ (completely Hausdorff) space each of $\left({S_\alpha, \tau_\alpha}\right)$ is a $T_{2 \frac 1 2}$ (completely Hausdorff) space.