equipment for testing circuit boards subassemblies and circuit board components, namely, test adapters, contact plates, and testing and measuring tables; and accessories for said testing equipment, namely, data recorders and attached printers and data recorders, test adaptor housings and frames, socket connectors for test adapters, mechanical holding down devices and clamps, and vacuum devices, namely, vacuum pumps, vacuum ducts and vacuum control valves; and positioning and feeding machines ...