SC 44.21 PRO4 24V SC 5 - 8 Ohm SC 5 8 OHM SC 5.9 - 8 ohm SC 5.9 8 OHM SC 5.9 FLX - 8 OHM SC 5.9 FLX, 8 ohm SC 5.9 ND - 4 ohm SC 5.9 ND - 8 ohm SC 5.9 ND 4 OHM