Latching relays are handy when you want to set a connection, then have it maintain that state until told otherwise. This Grove module plugs in, and sets the double-pole, double throw relay into a position depending on the pulse sequence it receives.

A “Low/High” signal ties the common and “NC” pins together (pins 4&6, 13&11)

A “High/Low” signal ties the common and “NO” pins together (pins 4&8, 13&9)

Once the position is set, the relay requires no more power to keep that position. Kind of handy when you want to set it and make sure it stays that way!