This 7/16 DIN Male/Female DC stop prevents DC voltage from being shorted in power over coax systems, where mast head amplifier is not used.  Typically the mast head amplifiers are fed power over coax via Bias T, feeding power to multiple antennas in 900Mhz and 1.8GHz bands. Also used if power is fed up the tower without using amplifier at any antenna. The unit provides excellent loss & VSWR characteristics with high isolation between the two ports.