FFP3 Moulded Face Mask with Valve | EN149 NR (Box of 10) The particulate respirators are designed to protect against solid and non-volatile liquid particles. The masks are held on the face by a pair of elasticated straps. The models are single shift devices. (Denoted by the classification symbol NR) Standards: EN149: 2001 A1: 2009 – Respiratory Protective Devices.