This is the FLOWMAX Carburetor Restrictor from Ultimate Racing. With an innovative design, longer than the standard O.S. venturis and wider at the base, unlike all others, makes the inferior part of the venturi and the carburetor have exactly the same diameter. This new geometry improves fluid dynamics, providing extra power that allows the use of smaller venturis without decreasing power, and as a consequence improves fuel mileage.

It is made of aluminum, laser engraved to differentiate the size at a glance and red anodized. The top is grooved for easy removal. Available in 6 and 6.5mm.