Hand-held megaphones with whistle and siren signal for general use: sports and school activities, demonstrations, construction sites, traffic control ... The 15 W model (JE-303ASW) has a range of about 300 m, 8 hours autonomy in voice reproduction and is recommended for groups of up to 200 people. The most powerful model (SJM-740SW) of 35 W has a range of about 400 m, 10 hours autonomy in voice reproduction and is recommended for groups of up to 350 people. The SJM-740SW can be used both handheld or with a strap to hang on the shoulder, as it has a stand-alone microphone that can be detached from the body of the megaphone. This feature and its greater power allow its use in more demanding conditions, such as military exercises, fire or police stations or noisy streets.