SP 4.500 is the first Hertz amplifier featuring the renewed Hertz ADC (Advanced D-Class) output stage, reaching up to 85% efficiency and delivering an impressive power rating of 90 x 4 (4 Ω) W RMS or 300 W x 2 (4 Ω) W RMS when bridged, with an ultra-compact size of 192.7 (7.58) x 130 (5.1) mm (in.) x 49 (1.9). Being ultra-compact with impressive power, SP 4.500 is the ideal choice for Motorcycle applications and for under-seat in sports cars and behind-seat installations in trucks.