I use an Aputure Pro Coworker, $15 on Amazon. I've used it a far away as 150 feet. The units can be used as both a wired and wireless. I've used in at 150 feet witha house between the units. One unit uses a couple of AAA cells and the other uses a 23A battery, and I remove the 23A battery to keep the battery from being discahrged. The only negative I have have about the unit.