1-10 HP™ & 1-10 HPS™ Concentrate System Refills are insecticide refills for 55 and 30-gallon automatic spray systems. Developed over 40 years ago using the highest quality pyrethroids, HP is a premium formulation that has set the bar for effective automatic flying insect control. It provides both quick knockdown and long lasting protection against a broad range of harmful biting insects that include: Horn Flies, Deer Flies, Stable Flies, Face Flies, Midges, Mosquitoes and more.