( BLACK ) The ALTA line is characterized by a thin and tapered cabinet geometry with a high-gloss, lacquered finish. The box design reduces standing waves, leaving the precision crafted woofers to reach their potential and deliver pure, well developed sound. With either the fl oor standing AL51 tower with four 5.25” woofers, AL41 plasma style with three 4” woofers, the AL31 bookshelf or the ALC center, a balanced audio tonality is assured. Furthermore, the entire series is magnetically shielded and is equipped with tetetron tweeters and elaborate crossovers. Choosing a stylish ALTA system is easy. Couple an ALC center channel with the AL51 towers, the AL31 satellite models for great sounding stereo and home theatre. Model AL31 2-way Woofer 102mm / 4 “ Tweeter 19mm / 0.75 “ 20 ~ 100 w Suggested amplifier 120 Hz ~ 20 kHz frequency response 6 Ohms 87 dB sensitivity 5.6 kg 12.1 lbs 241 x 140 x 165 mm 9.5 x 5.5 x 6.5 inches Warranty : 90 days.