Cartesian Product is Small iff Inverse is Small

Theorem
Let $A$ and $B$ be classes.

Then the Cartesian product $A \times B$ is a small class $B \times A$ is small.

Proof
Let $B \times A$ be a small class.

Then, by Inverse of Small Relation is Small, $A \times B$ is also small.

Similarly, let $A \times B$ be small.

Then, by Inverse of Small Relation is Small, $B \times A$ is also small.