This Relay as it says, is an M5Unit that implements relay functions. The relay can be used as an electric operated switch, using an electromagnet to mechanically operate a switch where it is necessary to control a large power load circuit by a separate low-power signal such as digital signal output from a microprocessor. The Relay support input voltage goes up to 30V DC and 220V AC. There are 3 pins named: ON, OFF, and COM. You can program it to make COM connect to ON or OFF, just like high and low output of a digital GPIO. Features Single-BUS control Up to 3A @ 30 V DC or 220 V AC Software Development Platform: Arduino, UIFlow (Blockly, Python) Two Lego-compatible holes Package Contents 1x Relay Unit 1x Grove Cable 1x 3.96 soket Specifications Resources Parameter Net weight 12g Gross weight 26g Product Size 48 x 24 x 21mm Package Size 60 x 57 x 17mm Resources Documents