The Powa™ Valve Pack contains 2 Powa™ Valves that can be used in the majority of Respro® Masks (with the exception of the Metro™ Mask). These valves have better breathing characteristics at higher airflows, i.e. when breathing heavily in sports or when engaged in strenuous physical exertion. You can use Powa™ Valves with Techno™ Filters or vice-versa. The Sportsta™ Filter gives better inhalation characteristics over the City™ Filter and the Techno™ Filter. This combined with Powa™ Valves is why the Sportsta™ Mask is perfect for use in sports activities.