4Life Transfer Factor Classic has been recognized for years as the best colostrum-based Transfer Factor product for daily immune system support. It contains our original Transfer Factor XFÂ® ingredient for safe and proven immune support. Primary Benefits: Transfer Factor supports your body's ability to remember past invasions, promoting efficiency and health within the immune system. Educates naive immune cells about a present or potential danger in your body along with a plan for action. Supports the recognition phase of a health threat. Provides balance to the immune system.