An SMA (SubMiniature version A) connector is a type of coaxial RF (Radio Frequency) connector widely used in telecommunications and other industries for connecting RF cables with antennas, RF devices, and other equipment. 

Here are some key features of SMA connectors:

1. Threaded Coupling: SMA connectors feature a threaded coupling mechanism, which ensures a secure and reliable connection between the plug and the jack. This threaded coupling provides better stability compared to push-on or snap-on connectors.

2. Frequency Range: SMA connectors are designed to operate within a wide frequency range, typically from DC (Direct Current) up to 18 GHz or higher, depending on the specific type and construction.

3. Size and Gender: SMA connectors come in various sizes, including SMA (standard), RP-SMA (Reverse Polarity SMA), SMA 905, and SMA 906. They are available in both male and female versions, with the male connector having internal threads and the female connector having external threads.

4. Applications: SMA connectors are commonly used in applications requiring high-frequency signals, such as wireless communication systems, antennas, RF test equipment, and instrumentation.

5. Compatibility: SMA connectors are standardized, ensuring compatibility between different manufacturers' products. However, it's essential to note that there are two main variants: standard SMA and RP-SMA, which are not compatible due to reverse polarity.