1 Way Relay Module Low Power Trigger Relay Expansion Board 1. This module complies with international safety standards, with isolation slots between the control area and the load area 2. Using relays, with power and relay action indication, absorb bright, disconnect not bright 3. When there is signal at the signal input, the common terminal and the normally open terminal will conduct 4. It can be used as a microcontroller development board module, and can be used for home appliance control 5. Control DC or AC signals, can control 220V AC loads 6. There is a normally open and a normally closed contacts 7. Blue KF301 terminals to connect the control line is more convenient 8. Weight: about 12.4 g 9. Size: about 4.3 x 2.7 cm About the high level and low level trigger mode description: 1. High level triggering refers to the triggering mode where there is a voltage between the signal input and ground, which can be understood as a mode of triggering by short-circuiting the signal input and the positive pole of VCC 2. Low level trigger refers to the trigger mode where the voltage between the signal input and the ground is OV, which can be understood as a mode where the signal input is triggered by a short circuit with the negative pole of GND