Added carbon layer helps relieve workers of nuisance levels (less than OSHA Permissible Exposure Limit) of ozone and organic vapor odors. Suitable for most welding fumes. Fits easily under welding hoods. hangs loose Exclusive HandyStrap® allows mask to conveniently hang down around the user’s neck so it’s always ready for use. And during wear the adjustable cloth strap feels comfortable and cool.