RB250GS is an Ethernet switch. 

It has five Gigabit ethernet ports powered by an Atheros Switch Chip. 

It is powered by a new operating system designed specifically for MikroTik Switch products - SwOS. 
SwOS is configurable from your web browser. It gives you all the basic functionality for a managed switch, plus more: Allows to manage port-to-portforwarding, apply MAC filter, configure VLANs, mirror traffic, apply bandwidth limitation and even adjust some MAC and IP header fields. 

Box contains: RB250GS, plastic case, power supply