GVS PR450 Elipse Replacement Nuisance Odor Filters, Both Small/Medium and Medium/Large. Replacement filter to the GVS Ellipse half mask safety respirator. P100 HESPA nuisance odor filter that has a filter efficiency of 99. 995% in a small, lightweight and flexible filter. designed to remove low level odors and gases that could be unpleasant as well as harmful to health. Sold as a set (2 filters) and fits both S/M or M/L size masks.