&lt;p&gt;The TU-631 is a highly intelligible driver unit suited to public address announcement applications. Use the driver unit in combination with a suitable horn (optional). Its powder-coated finish and stainless steel screws ensure the unit&amp;#039;s weatherproof capability.&lt;br /&gt;&lt;br /&gt;Applicable Horns TH-650 TH-660 &lt;br /&gt;Rated Input 30 W &lt;br /&gt;Rated Impedance 16 &amp;Omega; &lt;br /&gt;Sensitivity 110 dB (1 W 1 m) (When operated with JIS C 5504 standard horn.) &lt;br /&gt;Frequency Response 150 Hz - 6 kHz (When operated with JIS C 5504 standard horn.) &lt;br /&gt;Dust/Water Protection IP65 (When a driver is operated with a horn.) &lt;br /&gt;Horn Coupling 1 - 3/8 18 threads (inch screw) &lt;br /&gt;Polarity Hot: Black Com: White &lt;br /&gt;Operating Temperature -20 %%dC to +60 %%dC (-4 ???F to +140 ???F) (no condensation) &lt;br /&gt;Finish Flange: Aluminum gray powder coating&lt;br /&gt;Rear cover: ABS resin gray&lt;br /&gt;Screws: Stainless steel&lt;br /&gt;Speaker cable: Polyvinyl chloride insulated cabtyre cable&lt;br /&gt;(6 mm (0.24) in diameter 600 mm (23.62) in length) &lt;br /&gt;Dimensions %%c139 ? 106 (D) mm (&amp;phi;5.47 ? 4.17) &lt;br /&gt;Weight 1.4 kg (3.09 lb) &lt;br /&gt;Option Driver unit cover: UC-200A&lt;br /&gt;Matching transformer: TM-30T TM-60T &lt;br /&gt;&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;