My house is built so that the master bedroom is upstairs and the bedrooms are downstairs.
We just moved our baby from the master bedroom to one of the downstairs rooms now that he's largely sleeping through the night. I built a video/audo monitoring system so we could watch him constantly from upstairs. His crib has a battery powered mobile with a remote that he loves. However, we couldn't turn it on at night without waking him up fully.
I bought one of these remote extenders. I wasn't sure it would work on a baby mobile IR, but it did. We can now turn on the mobile from 50 feet away in our master bedroom without fully waking him up. He listens to the music and goes back to sleep.
If this works with a baby mobile remote, I'm pretty impressed.