NACA ducts for motorsports and experimental aircraft builds. Inline blower fans, air plenums and NACA ducts used for brake cooling, critical component cooling and fresh air delivery to the cockpit of race cars. Dual 4" NACA ducts, Single 3" and 4" NACA ducts, 3" and 4" air plenums. Inline blower fans in 3" 180cfm and 4" 285cfm with high pressure - low amp draw.   ** Free Shipping on orders over $200 to the lower 48 states **