The patented Mosquito is a small speaker that produces a high frequency sound much like the buzzing of the insect it's named after. This high frequency can be heard by young people 13 to 25 years old. The latest version of the Mosquito is called the MK4 Multi-Age. It has two different settings one for teenagers 13 - 25 years and one setting for all ages. When it is set to 17KHz the Mosquito can only be heard by teenagers approximately 13 to 25 years of age. When set to 8 KHz the Mosquito can be heard by all ages.