Vent-Guard is a vent stack device for eliminating toxic sewer gas and odor egress and migration to nearby rooftop HVAC system outdoor air intakes. The patent-pending Vent-Guard is available in three sizes designed to fit 2, 3, and 4 inches diameter commercial building plumbing vent stacks and restaurant grease interceptor vents. Constructed of sturdy EPDM rubber. Top is infused with carbon black that is resistant to ultraviolet (UV) light. Quick, easy and inexpensive alternative to charcoal filter vent stack attachments that require periodic cleaning and replacement. Unique design allows airflow in and eliminates insect, animal, inclement weather, bird nesting infiltration.