A red Model 20
A yellow Model 20
A white Model 20
A ad stating the siren
The Model 20 siren is a omnidirectional siren that is made by Fedelcode. Despite it calling being it called the "Model 20" it turns out to be a bigger Fedelcode 5/7. An example: https://www.youtube.com/watch?v=Me6hdihSRUc
People found out that they're callled Mach 10s. Also, they were called Mach 5s.
According to this ad, the siren can be coded. It could be possiable that it was the first siren to do hi-lo?
A pink Model 20