The Wolo 4100 is a 12-volt, 100-watt full feature electronic siren and PA system designed for emergency service responders who demand a powerful and reliable electronic siren system. Select from three-(3) different siren sounds (Yelp, Hi-Lo and Wail) by using the rotary control. There is also a manual override control switch that the user can press and hold that will provide short blasts of two-(2) additional siren sounds; air horn sound or a fast yelp siren sound. Model 4100 also includes a P.A. system that has a noise-canceling microphone permanently mounted to the siren controller that will produce high quality voice amplification without feedback or squeal. The microphone’s push to talk button has been designed to override any siren sounds in use for PA on demand. Model 4100 easily wires to the vehicle’s radio for rebroadcast. All siren sounds, P.A. system and radio rebroadcast have an adjustable volume by using the rotary on/off control, which is located on the siren’s illuminated front control panel. Recommended speaker either Model 4002 or 4003, speaker sold separately.