AEDIKO DC 12V Relay Module 8 Channel Relay Board with OPTO Isolated High or Low Level Trigger Compatible with Raspberry Pi Arduino UNO R3 MEGA 1280 DSP ARM PIC AVR STM32 sold2025 makes it easy to carry B01LD6AS2E makes it easy to carry the TX Tool wherever you go Product Size:3 4" Thread Female The Relay Is Suspended Before The Suction and It Is Short Circuited With COM After The SuctionCOM1 COM8: Common Interfaces of the 8 Channel RelayNC1 NC8: Normally Closed Interface of Relay and It is Shorted to COM Interface Before The Suction is Closed High and Low Trigger Selection: S1 S8 are the High and Low Level Trigger Selections of Relay 1 to 8 in SequenceCOM is Shorted With Low Trigger Current : 5mA