The 81FHW woofer was designed with smaller hi-fi subwoofers in mind. The woofer works well in vented enclosures or combined with a passive radiator. Optimized magnetic structure delivers good level of performance and balancing well performance vs cost. We have chosen lightweight foam surround in this design. Our extensive development and testing of this material yielded in custom formulation of the raw material we use for the surround and guaranties its long lasting performance.