2 channel SPDT 10Amp power relays, High quality Panasonic JS1-12V-F relays. Opto-Isolated for effective isolation between input and output circuits. High quality pluggable screw terminal blocks. Power supply reverse polarity protection, control signal reverse polarity protection. if you accidentally reverse these polarity, the module will not work, will not damage the module. LED indicator for each relay channel. Power supply ground(PGND) and Signal ground(SGND) separation design, you can also easily use short-circuit cap to connect together.