Ultrasonic repellers don't work well on mice long-term. Human hearing range is 20kHz. Mice apparently hear up to 100kHz, but if the sound doesn't bother you then is apparently won't bother mice either.
I have a sound-based have a sound-based repeller which is loud and audible. The frequency range is 3-40kHz so it is in human hearing range and it is loud. I have to turn it off whenever I got in the garage because it would drive me nuts. The owner of the building where we used to store our cars in the winter used them and said he never had problems with mice or other pests. One key is that it can make different annoying sounds. He would go into the building once a week and change the sound so the mice don't get used to it. I bought his from him when he sold the property. It's called a "Transonic Cix" by Applica. I searched online and couldn't find that brand name, but it's identical to this:. The frequency range is 3-40kHz so it is in human hearing range and it is loud. I have to turn it off whenever I got in the garage because it would drive me nuts. The owner of the building where we used to store our cars in the winter used them and said he never had problems with mice or other pests. One key is that it can make different annoying sounds. He would go into the building once a week and change the sound so the mice don't get used to it. I bought his from him when he sold the property. It's called a "Transonic Cix" by Applica. I searched online and couldn't find that brand name, but it's identical to this:
Transonic PRO | Bird-X Sonic/Ultrasonic Indoor Pest Control