Each hidden breather is o-ringed at the heads and exits at the mouth of the injector/carb to provide efficient engine breathing, eliminating the need for any external hoses or hardware. Standard red filters are pre-oiled, washable and feature four-layers of surgical grade cotton for optimum filtration and maximum airflow. One-piece aluminum backing plate features patented hidden breather technology. Radius air inlet provides maximum performance by providing unobstructed airflow. All necessary hardware and instructions are included.