Ableconn PIUSB2S2U USB to 2-Port RS232 DB9M Serial and 2-Port USB Stackable Expansion Board for Raspberry Pi Add two UART RS232 DB9M ports and two Type-A USB ports to your Raspberry Pi via an USB upstream connection. Optional 2-pin power wafer input for power hungery devices. Options of upstream connection via either an USB micro-B connector or an USB 5-Pin Pin Header. Supports UART data transfer rate up to 230 Kbps Includes Multi-Pi mounting accessory of standoff, nuts, and screws CE, FCC, and Fully RoHS compliant. Made in Taiwan