(Merck) Double Barrel VP insecticide cattle ear tags are organophosphate and synthetic pyrethroid tags containing 6.8% lambdacyhalothrin and 14% pirimiphos methyl. Double Barrel VP tags are approved for use on beef cattle, non-lactating dairy cattle and calves. Use 2 tags to control horn flies and face flies for up to 5 months. Use the Allflex Universal Total Tagger to apply. 9.5 grams.