All 4 indicator lights are on, then the data line is normal (double-head type-c data line requires all 5 indicator lights to be on). If VCC or GND is not lit, it indicates that the charging function of the data line is abnormal. D+ or D- is off, indicating that the data transmission function is abnormal. CC is dedicated to double-head type-c data line detection. When testing other data lines, the light not turn on. Colour: Black material: plastic Scope of Test Type-c to Type-c Type-c to Lighting USB to Lighting USB to Type-c USB to Micro 1. Use the type-c charging cable to plug into the power supply port to supply power to the product. 2. Insert one end of the data cable that needs to be tested into the corresponding port. 3. Insert the other end of the data cable into the corresponding port. 4. Observe the indicator light. Package Contents: 2 x DT3 Data Cable Detection Board 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.