PYthon® Magnum is a sustained-release, plastic ear tag containing a synergized formulation of zetacypermethrin, a potent, enriched S-isomer pyrethroid compound. This insecticide has excellent activity against many pests, including horn flies that are resistant to certain other insecticides. PYthon® Magnumʼs larger net weight of 15.4 grams per tag provides greater insecticide release for maximum effectiveness against horn flies and other ectoparasites.