Viper VaporCheck II (Viper II) is the first line of defense against damaging water vapor and soil gas threats existing below the concrete slab. Viper II products are multi-layer (co-extruded), virgin polyolefin under-slab vapor barriers/retarders. The virgin resin used to manufacture Viper II contributes to its long-term stability and prevents the material from breaking down when buried below the slab. Viper II is engineered with superior resistance against punctures, tears and water vapor. The high puncture resistance and tensile strength greatly reduces potential damage when exposed to rigorous job site conditions. Furthermore, Viper II products have very low water vapor permeance properties, key to preventing water vapor migration. All Viper II products are tested and engineered to meet and exceed the Class A, B and C requirements outlined in ASTM E 1745 (Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill under Concrete Slabs). ASTM E 1745 is the most recognized industry standard for under-slab vapor barrier/retarders.