These respirators breathe like they have a valve, without one. Wave technology allows easier breathing for cool comfort, providing the protection you need all day long. The filter is protected on both sides by Dura-Mesh® to keep the respirator clean-looking on the outside and collapse-resistant on the inside. Softspun lining is comfortable against the face. SmartStrap is an adjustable cloth strap that allows your mask to hang from your neck when not in use. For areas with an oil mist, use an R or P respirator.