Important Facts to Consider: Electro-Mechanical Warning Siren. No speakers or amplifiers here, just real, honest, big-time, worry free sound. 100% Maintenance Free. Not just a part of the siren, the whole system !! NON-ROTATING. Forget about the worries of rotating sirens, this unit only has two moving parts !! Mechanically produced sound - stronger and further reaching than electronically produced sound. Compatibility, this siren will integrate seamlessly with 99% of existing siren systems. Lifetime Tech Support is included with every siren. No matter how old your siren is, we will help you through any problems. FIVE YEAR WARRANTY so you can rest assured your siren will be functional at all times. The NRC (Nuclear Regulatory Commission) has given this siren family an expected useable life of 53 years!! Large enough to tackle almost any application, the Sentry Model 20V2T is at the top of its class. Taking advantage of a continuous duty industrial motor and rated at 124 dB at 100 feet, the 20V2T is an OMNI-DIRECTIONAL siren which produces continuous 360º coverage, making it a superior alternative to a rotating or directional beam type siren. The 20V2T is available in either single or three phase power, and is a dual tone siren, employing two rotors with different numbers of ports to produce a greater range of frequency. One rotor produces 460 cycles per second, and the other produces 920 cycles per second. The Model 20V1T is a single tone siren, with both rotors producing 460 cycles per second. All exposed siren components are of metal construction, which are "Powder Coated" for the most durable finish available. The fan and housing are made of non-corrosive cast aluminum. Maximum diameter of the Model 20V2T shall be 78", maximum height of 56", and maximum mounting base of 19" square. Shipping weight of the siren alone is 750 lbs.