5V 1 Channel Relay Board Module Active Low - Terminal Blocks

A very useful, small relay which draws little current through its actuator coil. (I've used this, amongst other things, for a home automation project to switch the mains supply to a central heating boiler.) Though listed as "active low", you can actually control whether switched by a high or low signal with a jumper. Very good value.
My only criticism is that, when mounted in an inaccessible position, it can be difficult to get wires into the screw terminals even when fully loosened.