For metric spaces $(M_1, d_1)$ and $(M_2, d_2)$, it is an exercise that the product topology on $M_1\times M_2$ is induced by the metric $d=d_1 + d_2$.
Do you know if this statement generalises to premetric spaces?
Here, we call $(M,\tilde{d})$ a premetric space if $M$ is a set and $\tilde{d}:M\times M\rightarrow[0,\infty)$ is such that $\tilde{d}(x,x)=0$ for all $x\in M$.