A rigid, extended surface air filter, engineered to provide maximum performance and prolonged filter lifecycles, even in the most difficult environments. The durable, rugged construction of the DuraMAX 4vS make it the filter of choice in filtration systems with high velocities or variable air volumes. Constructed with an all plastic frame so it is easily incinerated after use. Provides an unequaled combination of low pressure drop and high efficiency through the use of our unique minipleat design.