A close-up of the ISIS Mastercell shows the weather-proof enclosure, which is sealed with watertight gaskets for maximum protection. All enclosures feature clear covers for easy system status checks. All plastics used in the construction of the enclosures are UL 94V0. Bases are glass-reinforced, high-temperature nylon for strength and temperature resistance, while the covers are made of high-temperature polycarbonate. A single Mastercell input unit can control up to five Powercell control units for a total of up to 50 functions. All mating electrical interfaces use top-of-the-line Delphi Packard sealed connectors.