Adopt CH340 to Serial Port chip,stable performance,good compatibility Adopting the 3225 SMD crystal can promote the working stability of sercial port and be elegant with high end This module is USB to Serial Module and in charge of making USB port convert into the suitable ESP8266 Serial Port Module Working voltage: 4.5V - 5.5V (On-board 3.3v LDO Regulator) Working current: 240mA(MAX)