This is quite an innovative product with a duel purposes. At one end it clips onto the fence and at the other has a prong which goes into the soil. With the pulse given out by the energiser the tube in the middle has a few small but very bright lights which flash.
You can hardly see them during the day but at night you can see them from a distance. They will flash unless the power drops below 2000v. Perfect if you can see your fence from the house and like to have some reassurance that the electric fence is working well.
The intermittant flickering also irritates any nocturnal predator like foxes or badgers that may wish to try their luck getting to your chickens and acts as a very good humane deterrant. Very popular with smallholders and people with a few birds. Just hang on the chicken net
at any vulnerable points (gateways, dips in the ground, etc) for that extra peace of mind.