They emit an audible sound as well as red light signal to indicate breaker point opening and closing. These static timers and continuity testers enable checking of the continuity of circuits as well as connections. They offer long lasting durability and this one includes a new 9 volt battery so you are ready for action when it shows up on your doorstep.
Note: This is a used item. This item might have been taken in on a trade. RBS may have inspected this item and deemed re-usable. There is no warranty expressed or implied with this item.