The Y-TEX XP 820 Insecticide Cattle Ear Tags Ranch Pack contain new insecticide abamectin, a highly active macrocyclic lactone that is particularly effective against horn flies, including strains resistant to synthetic pyrethroid and organophosphate insecticides. The pack's new chemical class makes it ideal for rotation with any other insecticide tag. The slow release formula contains synergist piperonyl butoxide to increase potency. You can use 2 tags to control horn flies up to 5 months, control ticks up to 4 months and reduce face flies. You can use 1 XP-820 ear tag to control horn flies up to 3 months. This ranch pack is approved for use on beef cattle, non-lactating dairy cattle and calves.