At specified concentrations in Methanol. Standard includes: Benzene, Ethylbenzene, n-Heptane, 2-Methylpentane, 1,2,4-Trimethylbenzene, 2,2,4-Trimethylpentane, Toluene, m-Xylene, o-Xylene, p-Xylene. Stores refrigertaed. A NIST traceable reference material. 1.5mL ampule.