Forged billet aluminum backing plate features Big Sucker* hidden breather technology and a radius air inlet for smooth airflow, Forged billet air filter covers feature exposed design and a CNC inverted top that acts as a velocity stack to help pull in more air flow, Hidden breathers are O-ringed at the heads and exits at throttle body/carb to create a virtually closed-loop system, Performance filters features a black synthetic filter element wrapped in a stainless steel jacket, Black stainless steel jacketed inverted filters feature an inverted pleated top and 360? of pleated sides to pull in filtered air from every angle, CNC-machined from forged billet aluminum, No external hoses or hardware needed, Made in the USA