This is 3 pieces of 5V 1-channel relay modules that work with Arduino, ESP32, ESP8266, Raspberry Pi, or any 5V or 3.3V microcontroller. A single package includes 3 pieces of relay modules.

SPECIFICATION:
- Normally open and normally closed.
- High-level trigger or low-Level trigger selection by a jumper.
- Optocoupler isolation.
- Terminal blocks for both input and output.
- Two LED indicators: power (green LED), the relay status (red LED).
- Fault-tolerant design, even if the control line is broken, the relay will not operate.
- Operating voltage (power): 5V.
- Trigger voltage: 3.3V to 5V.
- Trigger current: 5mA.
- Maximum load: AC 250V/10A, DC 30V/10A
- Dimension: 50mm x 26mm x 18.5mm (L x W x H).

INPUT INTERFACE:
- DC+ : Connect the positive pole of the 5V power supply.
- DC- : Connected the negative pole of the 5V power supply.
- IN: Signal trigger input (3.3V to 5V, high or low level signal selected via a jumper).

OUTPUT INTERFACE:
- NO: The normally open interface.
- NC: The normally closed interface.
- COM: The common interface for both normally open and normally closed.

High/low level trigger selection jumper:
- If the jumper is placed between COM and L, the relay uses LOW level trigger.
- If the jumper is placed between COM and H, the relay uses HIGH level trigger.

HOW IT WORKS:
High Level Trigger:
- When IN is LOW level signal, the NO does not connect with COM and the NC connects with COM.
- When IN is HIGH level signal, the NO connects with COM and the NC does not connect with COM.
Low Level Trigger:
- When IN is LOW level signal, the NO connects with COM and the NC does not connect with COM.
- When IN is HIGH level signal, the NO does not connect with COM and the NC connects with COM.

TUTORIALS:
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Tutorials for Arduino, ESP32, ESP8266, and Raspberry Pi can be found on product page by searching: DIYables 5V relay