Eliminate rats and mice in one feeding using the Pied Piper Wax Block Rat Bait. The active substance brodifacoum gets to work straight away. Simply place the wax block in bait box, in an area where you feel there is vermin, and leave the vermin do the rest. Once they bring this block back to the nest, it will eliminate the pests in one feeding. These are dangerous blocks and are harmful, please where gloves when applying and keep out of reach of children.