Will the signal go through a concrete block wall?

Thank you for your question. The wireless range is around 80ft-100ft in the free area, but the range will be shortened by electronic devices, walls, or other physical barriers, especially metal objects. Please check the range and if there are some metal objects between the remote and receiver, like the receiver is placed in a metal box. And when wiring the receiver kit, please put the wires behind the receiver kit. Please feel free to let us know if you have more questions. Best regards, support@suraielec.com Suraielec Customer Service

Can i add this to a switch that is already controlling 2 other suraielec outlets?

Thank you for your question. Yes, this 3-way switch can be programmed and paired with our other wireless wall switch sets. Please note the wall switch is a little different from the prior wireless wall switch sets, so as the color. All of our products come with a worry-free 1-year warranty and friendly 24-hour customer service. Please feel free to let us know if you have more questions. Best regards, support@suraielec.com Suraielec Customer Service

can this be used with an existing light switch to make it a 3 way? or does the existing have to be replaced? how are the units paired .. i ahve 2 circ

Yes and No. Your wired switch must be on sending power to the light for the two wireless switches to work remotely. If you shut off the light using the wired switch, the remote switches will not work. Hope this answers your question.

I have 3 recessed ceiling lights controlled by 2 wall switches. Can I use this product to add a 3rd wall switch ?

Thank you for your question. The wireless wall switch can't work the traditional 3-way light switches. The origianl 3-way switches need to stay on so that the wireless wall switch can work. If you need 3 wall switches, you need to add 3 wireless wall switches. All of our products come with a worry-free 1-year warranty and friendly 24-hour customer service. Please feel free to let us know if you have more questions. Best regards, support@suraielec.com Suraielec Customer Service