Mice repellent gel

People who want to get rid of mice can now buy a range of ultrasonic mouse repellent devices and electronic mice repellent equipment, as well as mice repellent sprays, which claim to deter and get rid of mice. But do any of these mice repellent products work? What is the evidence that they have any effect on mice infestations in homes? And are they worth the money, given that some can cost up to £50?