what is the maximum or estimated distance that this remote will reach?

It says up to 80 feet and thru walls too - we have done it from about 40 feet and thru walls, but haven't tried further as there was no need. Make sure if you buy more than one you check the frequencies are all the same if you want one remote to operate all of them. If you want them to function separately, buy different frequencies for all. I think they have them for indoor too!