Whole House FM Transmitter3.0 (2 Pack)

On battery power it's Okay. Most of the advertised functionality is there and works well enough. A few caveats:1) The microphone input is the 2.5mm size, which makes it annoying to remember an adapter every time it's moved or the configuration is changed. That also creates another layer of troubleshooting when trying to figure out how to get it set up.2) Then this thing eats through batteries. You could use rechargeables, but with the volume of them you will use, that's another inventory and process to manage, not ideal when this is part of a bigger life that you want to enjoy. But DO plan to use batteries, because...3) The major flaw is if you try to power it from the wall / AC in order to avoid burning batteries. The signal then includes a very high-pitch whine along with the desired sound, which even if you aren't using this for music or other entertainment purposes (such as a baby monitor, where all you care about is the presence or absence of crying), it really gets annoying to listen to after a while.Well-intended features and flexibility of configurations, but they have a lot of kinks to iron out in future models.

The Whole House 3.0 transmitters, although they claim to be certified, are WAY over the legal FCC limit for field strength. Use of one of these (even on the low power setting) are illegal in the USA and may get you a visit from the FCC. I'm a broadcast engineer of 40+ years who is actually a supporter of Part 15 broadcasting. I've tested quite a few Part 15 transmitters. This is just another one that's not legal. Use at you own risk.