HALYARD MICROCOOL Gowns meet the AAMI Level 4 liquid barrier standard. The Association for the Advancement of Medical Instrumentation (AAMI) developed the liquid barrier standard to assist healthcare personnel in the selection and use of surgical gowns, drapes and other protective apparel. HALYARD MICROCOOL Gowns are Level 4, the highest barrier protection rating available for gowns. The new HALYARD MICROCOOL Breathable High Performance Surgical Gown is the result of years of research to make MICROCOOL* more cool and protective than ever. Halyard Health has a long heritage of medical fabric leadership, with over 650 US and international patents for advanced non-woven fabrics. Patented Microporous Fabric: Soft spunbound outer layer; Proprietary breathable fabric; SMS fabric inner liner layer.