I have used in the past, but can't find now, even with x10 phone and computer support, one of the worse companies I have found for help.
It is basically a wireless 3 way switch, battery powered, not even 1/2" thick, secured with double stick tape.

Just now, while writing, got off the phone with W10 tech support again, and the new person I spoke with says he never heard of it?

I know they make. Anyone with the part number, it would be greatly appreciate it. Their computer and phone support took all my time and will have to check eBay or Amazon later, if no one here is familiar with it.
Thanks.

Home Automation sells some X10 wireless switches, good place to start. Slimline Switch Decorator White - SS13A

Thanks Ballenger, I am looking for the one that looks like a single decora style switch. Take Care