The CJ CT304D-800S is a TRIACs TO-252-2LK RoHS semiconductor device. It is designed to regulate the flow of electric current by controlling the voltage output from the device. It is composed of two thyristors, which are switching circuits that can be turned off and on. The device has an operating voltage of 800V and a current rating of 30A. It is RoHS compliant, meaning that it meets the regulatory standards for hazardous substances contained in electronic equipment. It is used in a variety of applications, including the control of lighting systems, appliance motors, and heater circuits.