Uses ultrasonic pulses to keep parasites, which are often the cause of asthma and allergy symptoms, away from the bed, carpet and the whole house. The ultrasound prevents dust mites in particular from reproducing. Works without chemicals or fragrances. The ultrasound works at a frequency of 40 kHz, which is imperceptible to humans and pets. The parasites are not killed but repelled, preventing them from reproducing. Device for indoor use. Can be operated via a power socket (220 V).