Time relay type "RV-4" specifically "RV-4-1 U4".

Time relays, timersThe time relay of the "RV-4" type specifically "RV-4-1 U4" has been produced presumably since 1975. Designed to turn on or off the load in the interval 1 ... 60 seconds. A photo enlarger lamp or a signaling device can be connected to the relay when carrying out photographic work, etc.