McGrath RentCorp helps clients who are short on space. Through subsidiaries, the company rents and sells commercial storage and containment equipment. Its largest subsidiary is Mobile Modular Management Corporation, which rents portable buildings used as classrooms, field offices, or rest rooms. Enviroplex makes and sells buildings which are primarily used in California public schools. TRS-RenTelco rents and sells electronic test equipment for communications and other needs, while Adler Tank Rentals offers containers used for storing hazardous and nonhazardous materials. Rentals and rental-related services account for around 80% of McGrath's total revenues.