At specified concentrations in Methanol. Standard contains: Benzene, Ethylbenzene, MTBE, 2-Methylpentane, Naphthalene, n-Nonane, n-Pentane, Toluene, 1,2,4-Trimethylbenzene, 2,2,4-Trimethylpentane, o-Xylene, m-Xylene, p-Xylene. Stores refrigerated. A NIST traceable reference material. 1.5mL ampule.