Standard Procedure Mask. Standard Procedure Mask with Earloops (NON27375) features a soft cellulose inner facing increasing comfort on the inside. Procedure Mask with Shield and Earloops (NON27420EL) features a soft, fluid resistant polypropylene inner and outer facing, assuring comfort on the inside and protection on the outside. A full-width nosepiece guarantees proper fit. BFE > 95% PFE > 98%.