Just One Bite II Bait Bars kill warfarin-resistant Norway rats, roof rats and house mice. Rodents may consume a lethal dose in just one feeding. Just One Bite II contains bromadiolone, a second-generation anti-coagulant rodenticide that causes internal bleeding. Death is delayed 4 to 5 days, so there's no bait shyness. Individually packaged 16 oz. bars.