When dealing with FPV video transmitters/receivers the most common connector used is SMA (SubMiniature version A).  These however come in different types and there is no true standard used throughout the industry: SMA and RP-SMA (Reverse Polarity).

When selecting and using gear and antennas you need to make sure you have compatible connectors so that they connect and function properly.

• SMA Male needs matching SMA Female
• RP-SMA Male needs RP-SMA Female

Always check what your gear uses before ordering matching parts.

There are adapters available if you need to connect from one type to another, as well as right angle connectors to allow mounting at 90 degrees.

Wikipedia – SMA Connector