Lighting direct have reduced the Sense-it security range, check the site
Basically its an infrared security detector that sends detection wirelessly to the receivers.
Movement sensor can be 9v battery or power supply (optional psu required), the chime and socket is mains powered.
Has an 8 way dip switch in each device to control frequency, plug in module has timer options.
I have sensor in my garage, turn a light on and alert me if someone opens it at night. Remote can be used to turn off or on. Loads of applications at a cheap price.