Features: Support TTL/RS232 standards, TTL signals can be converted to RS232 signals, full-duplex communication compatible with 3.3V ~ 5V TTL signal levels Onboards integrated power isolation with anti-reverse connection and anti-over-voltage circuitry on the power supply side provides stable isolation voltage. Isolated end without additional power supply on-board integrated digital isolation, signal isolation, with highly reliability, strong anti-interference and low power consumption and other features On-board TVS (transient voltage suppressor), can effectively suppress the surge voltage and transient spike voltage in the circuit. Support DC33.3V~5Vvoltage power supply industrial rail type ABS environmentally friendly housing, compact size, easy to install, cost-effective Specifications: Item：TTL to RS232 Converer Module Length:about 9.16cm/3.61in Support； DC3.3V~5V Package Includes: 1Set TTL to RS232 Converer Module note: Due to problemsof lighting effect and shootings, there will be tolerances in the product, please understand. Please allow 0-1cm error due to manual measurment.