The PZ4 has a dual-cavity, rugged anodized aluminum, line-grounded case that stands vertically. It can be attached to the pack or mounted on the wall. Under certain conditions it can even be set on the ground (in above ground pools installations for example). Air is supplied to the unit through filtering slots on the bottom to prevent insects from getting inside the unit. The electrical system is completely insulated internally in a separate sealed housing, and the ballast is mounted high above the base. In the event water inadvertently enters the ozone chamber, it simply runs past a completely insulated arc assembly and out through the slotted input filter