AirGuard's brushed grommets are made from flame retardant ABS polycarbonate plastic. The firm brush bristles are designed to create a near airtight seal around cables and other floor penetrations, helping to eliminate air leakage and control airflow bypass in underfloor air installations. The overlapping brushes are also effective at preventing passage of debris and contaminants from entering the air plenum system and causing damage to sensitive electronic equipment.