Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: What type of batteries are required in the sensor unit?
Document: Jan, 2013 UPDATE:The unit has failed again (yes, I tried a new battery.) It appears the transmitter is okay since I can see the little red LED illuminate when I wave my hand in front of the sensor, but there is nothing from the receiver. Now I have to decide about throwing this in the trash, sending it off for repair again, or shopping for another brand.
Other motion sensors I've used trigger 100%, so this type of failure does not occur with certain competitors. This difference may relate to the Dakota motion sensor only triggering on a narrow line, while competitors triggering on >90 degree range, which gives far more opportunities to try again after a missed event.
This thing works quite well in the warmer weather, but in the cold, with new batteries, it does not work at all.
I am completely satisfied with this driveway sensor. Nothing gets past it without us knowing about it.Thanks for a great product.
Bought this a couple months ago and it has worked flawlessly so far. Sensor is set between 1/4 and 1/2 mile from the house. Always goes off and so far no false alarms.
Unit has proven to alert without reliability. It does not work at all in the rain, nor if the car/truck is light colored.Look somehere else.
The unit sounds good but after talking to the manufacturer, they convinced me to cancel the order.I gave it 3 stars because I don't know how many stars it really deserves.
Do not buy from this company. I sure hope I hear from them and they send me a totally new complete unit that is tested for more than 5 feet so that I can remove this review.
Our old Optex would go nuts when the wind was blowing (not a tree within 50' of the gate), or would alarm when our antelope got too close to the gate.A very useful feature of this product is the ball mount of the IR sensor/transmitter which permits you to angle it to the best direction.
I purchased this unit last year so I would have warning when someone came up driveway. The problem is it warns when the wind blows, when a bird flies by, when the dust blows. Cannot depend on it as a warning device
Answer: 1 9v