USB Voltmeter ammeter voltageTC66 and TC66C difference: TC66 't have bluetooth board, 't support APP. TC66C have. Because firware is constantly updated, Please refer to the products actually received. When using TC66 to detect the charger, it is necessary to turn on the CC drop down. When using TC66 to detect the charging process of mobile phone, it is necessary to turn off the CC drop down. The switch ON the product is the power supply switch for the system. When in use, set it to ON. If the voltage is less than 3.5v, use -to supply power independently and set the switch to OFF. When TC66 USES the double-headed Typec line for the decoy triggering operation, only one side can be used. If it is not bright, please flip the interface. Colour:Black Material:Metal Package Contents: 1 * TC66 Type-C PD Trigger Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.