# Tensoring bounded maps on Hilbert spaces

Given two Hilbert spaces $$H_1$$ and $$H_2$$, together with two bounded linear maps $$L_i \in \mathcal{B}(H_i)$$, for $$i=1,2$$. What is the most easiest way to explain that the product $$L_1 \times L_2$$ extends to a bounded linear operator on the tensor product of Hilbert spaces $$H_1 \otimes H_2$$?