Pfizer - Long-lasting livestock pour-on is a ready-to-use, highly concentrated, waterproof formulation that contains 5% permethrin and .10% Pyrethrin plus the synergist piperonyl butoxide that increases the effectiveness of both insecticides. Patented water-repellent ingredient binds to the hair and won’t wash off. Approved for beef, lactating and non-lactating dairy cattle and calves. Controls horn flies up to 6 weeks, face flies up to 4 weeks and biting lice. No withdrawal for slaughter or milk. Use 3 ml per 100 lbs. body weight up to 30 ml per animal. Comes in a squeeze and measure.