21 Disk Playback Turntables, Stereo Disk Cutterheads, Condenser and Miniature Microphones, Power and Battery Supply Units, Microphone Interconnecting Cables, Band-Pass Filters, Light Signal Apparatus, Microphone Test Units, Microphone Stands, Adapter Plugs and Accessories, High Intensity Overload Protectors, Test Capsules, Power Supply Enclosures, Headphones and Headset, Pistonphones, Disk Recording Lathes