The Bose system in the Mercedes-Benz R129 SL-Class (between 1993-2002) features 7 speakers, was available as an option, at the expense of the rear seats. You could choose between the sound system and the rear seats. Seating was not available in the rear together with the Bose system, because the bass module with the attached electronics takes from the required seating depth in the rear, as you can see in the photos gallery.
7 High-performance speakers:
2x 16.5 cm mid and low-range speakers
2x 7.5 cm tweeters
2x 6.5 cm wide-range speakers
Under storage lid/rear seating area:
1x Bass module, housing one 13 cm low frequency transducer in a tuned, ported, 12-liter enclosure, featuring Acoustimass technology (a 6th-order bandpass enclosure, where both volumes are ported to the outside)
Attached to the bass module is the 4-channel amplifier with custom equalization.
Between 2000-2002, R129 made for the US marketplace, came stock with the Bose system consisting of:
Alpine Head Unit (Alpine CM1910, 208 820 11 86)
Alpine CD changer connected by fiber optic cable (Alpine MC3198, 002 820 79 89, located left side of trunk, CD cartridge 002 820 62 89)