The Tomcat Rat & Mouse Killer Refillable Bait Station - Advanced Formula uses an advanced formulation bait block that is more attractive to house mice (compared to the Tomcat Rat & Mouse Killer Child & Dog Resistant, Refillable Station EPA Reg. No. 90780-11). This refillable bait station can be placed horizontally or vertically indoors or outdoors to control Norway rats, roof rats, and house mice. The station is resistant to weather and to tampering by children and dogs. Each block of bait can kill up to three rats (based on no-choice laboratory testing). Bait stations with mouse and rat poison should be placed beside burrows, along walls, behind kitchen appliances, in corners, along the exterior of a home, and in basements, attics, and garages. If more than one station is being used, place them at 15- to 30-foot intervals. Each Tomcat Rat & Mouse Killer Refillable Bait Station has a clear cover to make it easy to monitor-when there is no more bait in the station, easily refill it with one of the provided bait blocks (use up to two blocks at a time).