Established in 1979, McGrath RentCorp, under the trade name Mobile Modular Management Corporation, rents and sells modular buildings to fulfill customers' temporary and permanent space needs in California, Texas and Florida. Mobile Modular is one of the largest providers of relocatable classrooms for rental to school districts for schools in California. The company's TRS-RenTelco division rents and sells electronic test equipment and is one of the leading providers of general purpose and communications test equipment in North America. Enviroplex, a majority owned subsidiary of the company, is a California-based corporation that was organized in 1991. It manufacturers portable classrooms built to California state standards and sells the units directly to the school districts. McGrath RentCorp is headquartered in Livermore, Calif.