SMA male to SMA female
Works well to extend an sma connector in e.g. a router where it does not fit, to make the connection to an external antenna a little more accessible.
Picture #2 shows the adapter mounted in the right socket of a Huawei B593 router, to illustrate how well you can access the antenna connector with it. Of course, the adapter works just as well on other routers with an SMA connector.
Delivered individually, the picture shows the adapter from two sides.