This duplexer is based on two PS2-3V bandpass filters.
Application range of these duplexers is very narrow. They can be used only for repeaters of multichannel sites with TX/RX frequency separation of 148/172 MHz. Passband of both arms of DPS2-6V duplexer amounts to 1.5 MHz, that`s why it is advantageous to use them for complex construction of sophisticated antenna-feeder systems at governmental buildings, where telecommunications engineers in the old way install "forest" of antennas, creating interference for their own devices.
Typical DPS2-6VM duplexer response curves