The SPEED BLEEDER has been designed with a built-in check valve. How this works, is that the next time you bleed your brakes, you will loosen the SPEED BLEEDER by 1/4 of a turn and then you pump your brake pedal. When the pedal is depressed, the pressure generated will open the check valve letting air and brake fluid out of the SPEED BLEEDER. When you let go of the brake pedal and return it to the up position, the check valve will close and prevent air from entering back into the system

When you are finished bleeding, simply tighten back the SPEED BLEEDER screw to prevent any more fluid from leaving.