A small gland that secretes oil containing very potent pheromones. This allows the user to immediately seduce any person who comes in contract with the oil. Usually used by concubines, it does have the side effect of severely shortening the life span of those who have them implanted. Where these glands come from is never made clear.
Commandant Mele-on Grayza has had a Heppel gland implanted in her chest. This has also caused the neckline of her clothes to extend to just above her belly button. When confronted by a Scarren in the episode Bringing Home The Bacon about her methods. She responds with, "Would you keep a weapon in your arsenal, and refuse to use it, simply out of squimish ideals of morality".