Instruction: Given a question and its related document, determine if the question is answerable by analyzing the information in the document. Output yes if the document addresses the question, or no otherwise.

Input:
Question: One viewer said you must insert 9-volt battery & connect plug to electrical outlet. I need both battery & house power?
Document: Insert a 9-volt battery into the switch and connect the plug to an electrical outlet and you now have remote control of a light source or (light-load) electrical appliance. The switch can be installed at a convenient location on the wall. Good useful product.
It works just like it's suppose to. However, it can be somewhat of an inconvenience to  have to unscrew the front to replace the 9 volt battery every time it needs replacing.Actually I was surprised that it even needed a 9 volt battery. The other one I had before didn't need a battery and it also had a night light, which this one doesn't.
I used to have a bunch of the original Handi switches that were light weight and had a big, led light on the plug in to let you know it was receiving power.This switch and plug has no LEDs and is very bulky in comparison. My initial switch does not work even though i put in the necessary 9 volt battery. (Handi switches come with their own batteries installed). So far, it looks like I won't be able to just order a Handi Switch knock off.
it will seem to stop working, however if you slow down to normal use it works well. one nice thing, the plug receiver/adapter covers only one outlet on a duplex. very simple and easy solution to a light weight switching problem. 9volt battery.
As some of the other reviewers have said, this simple approach to making an un-switched outlet, switched, is a great idea but I am having trouble with unintentional switching - probably from some other wireless device - and so far I can't find it. So the under counter lights I used this switch on are often on or off when interference occurs. I may need to hard wire the switches.
I have a couple that work. When they work, it is nice to have them. The range is awesome, it works from downstairs in the basement. You must have different radio frequencies, A , B, C, D, E,or F if you have more than one in the house because if you have same 2 of the same frequency, it will just turn the second item on or off when you turn the first one on from anywhere in the house.
Excellent product. I have had another one for 8 years. Still works. Add a switch without running wires through the walls! I even mounted mine so it was flush in the wall and looked like a regular wall switch. Just have to change the 9 bolt battery each year, plus or minus.
So far, I'm enjoying this switch. It has made it more convenient to turn on the lights in my living room, which has no wired lighting.However, I'm not enjoying the company, Heath-Zenith. I was in need of a second switch transmitter, but not a second plug-in receiver. I want to have two switches to control one lamp. The company refuses to sell the transmitters and receivers separately.
This switch is very handy. You just have to put a battery in it, but it works with everything all over the house.
When we moved into our apartment, We put our lamps on the side where the plug did not work with the switch. So when the product arrived, I took off the old switch and replaced it with the Wireless Switch and used the screws that it came with. The holes on the wireless switch match with the blue electrical box holes so it fits perfectly. I read that other reviewers are saying that it takes 2-3 seconds to turn on, fortunately mine works fine, no delay at all.
Answer: yes