Air Supply's new muffler has taken a quantum leap in quiet performance. The unique motor mount is the secret to our success. A thick rubber cup encases the fan while allowing the motor to vibrate freely on a flexible rubber base. This combination eliminates noise so well that virtually no foam is required. Many competitive blowers use filter foam to reduce noise, but the foam can clog over time causing starvation and overheating. Included with every muffler is a durable spring-loaded check valve. This is far more effective than flapper valves at stopping motor damage, meaning fewer service calls and more satisfied customers. Air Supply is committed to quality and service.