JACTO BACKPACK 4 GALSprayers by Jacto. Details: The very durable HD400 Series is extremely popular. The 4 gallon (16 liter) HD400 has an internal mechanical agitator that does an excellent job of keeping powdered chemicals such as kaolin clay organic insecticides in suspension, as well as liquid chemical additives. Independently tested for more than 1,500 continuous hours of operation with no breakdowns and easily converted for either right hand or left hand operation.