10Pcs 12V 1 Channel Relay Module With Optocoupler H \/ L Level Triger For Arduino  Feature:  Working voltage 12V High \/ Low level changeable Normally open interfaces maximum load: AC 250V \/ 10A， DC 30V \/ 10A Using SMD optocoupler isolation， driving ability， stable performance Trigger current 5mA Fault-tolerant design， even if the control line is broken， the relay will not operate The power indicator(green)， the relay status indicator(red) The interface design of human nature， all interfaces are available through a direct connection terminal leads， very convenient Size: 4.9 x 2.5 x 2cm  Module interface:  DC+: positive power supply (VCC) DC-: negative power supply (GND) IN: can be high or low level control relay  Relay outputs:  NO: normally open relay interface COM: common interface relays NC: normally closed relay interface  High and low level trigger options:  It is low level trigger when jumper connect to LOW pin It is high level trigger when jumper connect to HIGH pin  Package included:  10 x 12V 1 channel relay module