1、The frame is made of flame retardant plastic ,more safe to use. 2、Can working normally at the temperature between -5~40℃. 3、The current transformer is an instrument that converts the primary side large current into a secondary side small current according to the principle of electromagnetic induction. 4、The magnetic properties is made of copper core and the current transformer can be installed indoors. 5、According to the magnitude of the measured current, choose the appropriate current ratio, otherwise the error will increase. Features: The frame is made of flame retardant plastic ,more safe to use. Can working normally at the temperature between -5~40℃. The current transformer is an instrument that converts the primary side large current into a secondary side small current according to the principle of electromagnetic induction. The magnetic properties is made of copper core and the current transformer can be installed  indoors. According to the magnitude of the measured current, choose the appropriate current ratio, otherwise the error will increase. Specification: Model:BH- 0.66 Rated Voltage: 0.66KV Accuracy Level: 0.5 Current Ratio:150/5 250/5 300/5 350/5(Optional) Frequency:50~60Hz Core Turn:1 Frame Material: Flame Retardant Plastic Magnetic Properties Of The Magnet: Copper Core Installation Location: Indoor Ambient Temperature: -5 ° C -40 ° C Ambient Humidity: <80% Product Size: 6 x 8 x 3.7mm / 0.24 x 0.31 x 0.15in Package List: 3 x Current Transformer 3 Bag of Fixing Screw Bracket