Manna Pro s NEW Opti-Force Fly Mask provides Built-in, invisible, ordorless insect protection with Clear View Vision mesh. It protects & repels mosquitoes, ticks, ants, flies, chiggers and midges (including Lyme disease and West Nile). The comfortable design keeps the mask off the face and away from the eyes of the horse. Protects exposed areas around the mask, including muzzle and ears. Fits horses from 900-1200 lbs. Contains Active Ingredients: .52% Premethrin.