Spec Sheet Preview: The Alpha Communications® models OH600 and OH601 are flush mounting backboxes. The OH600 is made of galvanized steel and the OH601 is made of steel, painted in a Grey powder coat epoxy painted finish for durability, or in galvanized steel They are our most popular flush mounting boxes, and are used with a variety of flush mount intercom entry lobby panels, and remote intercom stations. The painted boxes are finished on top, bottom, both sides, and the back and both models have s …