37 maintenance, repair, installation and replacement installation of; radar systems, sonar systems and communication systems comprising transmitters, receivers, antennae, and display devices, computers, computer peripherals, and computer software for use in space vehicles, missiles, aircraft, watercraft, post office, insurance claim processing, and air traffic control applications; guidance systems comprising gyroscopes, lasers and inertial guidance sensors for space vehicles, missiles, aircraft, and watercraft; point-of-sale systems, comprising sensors, computers and displays; and parts for all the foregoing