RP SMA is reverse polarity of the SMA connector . It reverses the interface style. The RP-SMA connector is a shelled socket-style connector, but with pins instead of a center socket. The RP-SMA connector is an internally threaded plug-type connector, but with a central socket in place of the pins .
The connector is 50 ohm , made of gold plated brass , had been widely used for RF products .