The VariCel filter is a high capacity, extended surface, supported pleat filter engineered for a variety of applications. With a supported pleat media pack, the VariCel filter’s rigid construction maintains a compact, unitized structure even under difficult operating conditions, such as variable air volume, turbulent airflow, repeated fan shutdown, high temperature operation, high humidity, or intermittent exposure to water, such as seacoast installations. Variable air velocity and repeated fan shutdown do not compromise performance.