Theorem $\prod^{\left( A \right)}_{i \in n} \left( g_i \circ f_i \right) = \prod^{\left( A \right)} g \circ \prod^{\left( A \right)} f$ for indexed (by an index set $n$) families $f$ and $g$ of funcoids such that $\forall i \in n : \mathrm{Dst}\,f_i =\mathrm{Src}\,g_i$.