NulSom Inc. Ultra Compact RS232 to TTL Converter with Male DB9 (3.3V to 5V) Ultra compact board size:15 x 14 mm, FCC Certified Male DB9 Connector (RS232) Supports 3V to 5.5V power supply (***The Rx/Tx logic level is equal to the Vcc-supply.*** Vcc: 3.3V -&gt; Rx/Tx High Logic Level: 3.3V. Vcc: 5V -&gt; Rx/Tx: 5V ) Includes SP3232E [ Please consider NS-TRS232-02 (ASIN: B074BMLM11) for 1.8V or High-speed RS232 communication (up to 1Mbps) ] 4 pin through hole: VCC, GND, Logic out (TX), Logic In (RX) and 2 pin through hole: CTS, RTS