This unit group includes plumbing and other pipefitting trade contractors who own and operate their own businesses. This group also includes supervisors who supervise and co-ordinate the activities of workers classified in the following unit groups: Plumbers (7251), Steamfitters, Pipefitters and Sprinkler System Installers (7252) and Gas Fitters (7253). They are employed by construction companies, mechanical, plumbing and pipefitting trade contractors and maintenance departments of industrial, commercial and manufacturing establishments.