DS977 is the most common mechanical siren located in Czechia, and one of the most popular sirens to be ever installed in Czechia. The siren has been frequently exported into the Czech Republic (at the time Czechoslovakia), most likely from the 1950s up to 1990s, presumably as a part of good relations with the GDR (German Democratic Republic, also called East Germany). 

​

This siren is known to have a longer start-up to full speed (approx. 4,5 seconds) compared to other sirens like MEZ, which have a relatively quick start up. One of other known facts is that DS977 is one of the sirens which are able to run at 230V (single-phase electric power), which makes it a preferable civil defense siren for locations which have limited access to three-phase power. However, at a cost of extending the start-up time, due to lower voltage being delivered to the motor, therefore making the start-up slower. The siren can be recognized easily thanks to the start-up and its lower tone of 384 Hz. It has 8 ports.

​

The siren is a successor to S385, which is most likely not present in Czechia.
 

In the Czech Republic, there are 5 052 sirens registered within the JSVV (Jednotý systém varování a vyrozumění - Unified warning and notification system), from which there are 4 621 sirens actively in use. (as of 17/6/2021)