Pacific Resources CPL® Propolis Extract is nature’s defense system making it an essential ingredient for maintaining a healthy immune system. CPL® means Certified Propolis Levels and guarantees you're getting the highest quality, active propolis. Propolis extract is a complex chemical that consists of proteins, amino acids, vitamins, trace minerals, and flavonoids which is processed by honeybees from the resin they collect from trees and plants. The bees use this plant extract to seal their hives and protect it from infection. Humans use it as a natural or homeopathic treatment for a variety of medical situations.