Standard Speakers - Models 30.0205 / 30.0210 / 30.0219.BLK - High efficiency output. Nominal 375 - 8000 Hz. 120 dB - 10 feet on axis. 11 ohms at 1 KHz. Models 30.0205 and 30.0210 come with a black, injection-molded, ABS plastic bell. Model 30.0219.BLK comes with a spun aluminum bell ( painted black ). Standard mounting bracket permits full axis orientation. Field serviceable driver, voice coil, bell and tip. Works with any 100W siren. (Sold separately.) Standard Rectangular Bell, Model 30.0210, measures 5-1/4" H x 8" W x 6" D. The Low-Profile Bell, Model 30.0205, measures 4-1/2" H x 6-3/4" W x 6" D. The Round Bell, Model 30.0219.BLK, measures 6" H x 6" W x 5-1/2" D.