The Safe Flo SE Valve is a one-way check valve. The user inserts a standard saliva ejector into the end of the Safe-Flo SE valve. When the On/Off vacuum switch is opened, the vacuum system sucks air through the check valve and the aspirator tip. The check valve opens in the direction of air and fluid flow. Once the suction is stopped or blocked, the check valve closes and stops air and fluid from returning to the aspirator tip or the patient.