Sirens are used as alarm, warning or signalling devices. Thanks to their characteristic siren wail, they generate an unmistakable and penetrating alarm. A high volume wail with allround directivity is guarranteed and a suitably wide coverage range is attained. Different sizes and versions open up a broad range of applications, including signalling for critical situations. Used with the optional protection cover, the sirens are suitable for outdoor use. Sirens for special voltages and frequencies are available on request. The housings are made of die-cast aluminum and coated in light grey with weatherproof paint. The protection cover for models F0 and FI is made of weather-resistant plastic. The protection covers of other models are made of sheet steel and coated with weatherproof paint. With a protection cover, the sirens conform to protection degree IP 44 and the siren housing to IP 22. The sirens are designed for short time operation of 2-15 minutes according to VDE 0530, Part 1. For the power supply connections, the sirens F0 and FI are equipped with a cable gland Pg 9 and models FII and FIIb with a cable gland Pg 13.5.