All N95 respirators are NIOSH approved for protection against solid and liquid particles (at least 95% efficient); excluding those containing oil. Each respirator is disposable and designed to be comfortable, lightweight and easy-to-use. Model 8511 is available with 3M Cool Flow Exhalation Valve for added comfort. **PE**R-1 Warning Respirators are specifically designed for use in work applications where metal fumes may be present welding, brazing, grinding, metal pouring, etc. Each filter has at least a 95% efficiency for protection against solid and liquid particles excluding those containing oil. Welding respirators are disposable and available with a face seal or the Cool Flow exhalation valve. Also available with either acid gas or organic vapor relief. NIOSH approved.