When I saw the Repel A Pest I thought maybe I should get one for my girlfriend to take to Mexico with her next month so she doesn't catch the Zika virus. But after reading more about the ultrasonic device, it seems it's intended more for fending off (or at least it's more effective at fending off) mice, rats, and other rodents than bugs, so I'm going to get one for myself instead. She-Ra: Princess of Power's condo is nice and all, but with the crap rain and crap cold weather we've been having, I know I've seen some droppings in the kitchen that are not dropped bits of her apricot peach loose leaf tea.
Repel A Pest emits a piercing, high-frequency electromagnetic wave to deter scurrying home intruders from entering, or rattle those already there until they leave. Kind of like how some businesses play country music to discourage and chase away loiterers. Repel A Pest waves can hitch a ride on in-wall wiring as well, so pests won't want to enter or live there.
Repel A Pest is intended to dissuade roaches, spiders, ants, and other insects along with rodents, but most reviewers either didn't try or didn't have much success using it as an ultrasonic bug spray. They give it very high marks for its ability to end rat and mice problems.
Note: Repel A Pest makers say the device is safe for use in households with dogs and cats (and also humans and children), but it's not a good choice for pet owners with mice, hamsters, ferrets, or other rodent-like critters.