At 2000 ug/mL in Methylene chloride. Standard contains: n-Decane, n-Dodecane, n-Tetradecane, n-Hexadecane, n-Octadecane, n-Eicosane, n-Docosane, n-Tetracosane, n-Hexacosane, n-Octacosane. Stores at room temperature. A NIST traceable reference material. 1.5mL ampule.