1. The probe has elasticity, one handed operation, and is fast and efficient 2. Type-c ports, low power consumption, and long-lasting durability 3. With power indicator light, the optocoupler test board light flashes and the components are normal Instructions: 1. Place the optocoupler in the test area. If the control end light flashes and the controlled end light remains on, the device is functioning normally. 2. Test a four-pin optocoupler such as the 817 with a probe. Align the probe with the optocoupler according to the pinout on the board and down. If both the control end and the controlled end light flash, the device is functioning normally. Color:Green Material:Plastic+Metal Package Contents: 1 * Optocoupler Tester 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.