Disposable 3-layer NANO mask, breathability 200 l/m2/s, patented NANO fiber technology. Material bacterial filtration efficiency (BFE) ? 99.9%. Viral filtration efficiency (VFE) ? 99.9%, effectively filters virus-sized particles. It protects against the spread of viral and bacterial infections with the material's filtering function. Made in Czech Republic. The recommended time of use is a maximum of 12 hours. The product is intended for one-time use. Repeated use poses a risk of contamination and may result in reduced effectiveness. 50 pieces in a package