Amplifiers; Antennas; Calculators; Loudspeakers; Sirens; Amplifiers for wireless communications; Antennas; Antennas for radio, for television; Antennas for wireless communications apparatus; Cable television converters; Electronic components, namely, piezoelectric switches; Extension cables; Extension cords; Monitor signal amplifiers; Power adapters; Speaker enclosures; Stands adapted for tablet computers; Distribution amplifiers for audio and video signals; MP3 players; Television antennas