The RB411U is a versatile yet very small device. It includes all - a miniPCI slot, a USB 2.0 port and a miniPCI-E slot for connecting a 3G card. A SIM card slot for 3G is also present on the RB411U. RB411U includes RouterOS - the operating system, which can be a router, firewall, bandwidth manager, a mobile 3G router, and more - all at the same time. You can use the USB port to attach a secondary storage device, or a USB 3G modem. The RB411U mounting holes are in the same location as other RB411 models, so you can easily mount it into any supported outdoor case/antenna. RouterBOARD 411U with Atheros 300Mhz CPU, 32MB RAM, one LAN, one MiniPCI, one miniPCI express (for 3G), one USB port, one SIM slot, NAND Storage with RouterOS Level 4 (AP support)