def simtelArrayConfigFileName(arrayName, site, version, label):
    """
    sim_telarray config file name for an array.

    Parameters
    ----------
    arrayName: str
        Prod5, ...
    site: str
        South or North.
    version: str
        Version of the model.
    label: str
        Instance label.

    Returns
    -------
    str
        File name.
    """
    name = "CTA-{}-{}-{}".format(arrayName, site, version)
    name += "_{}".format(label) if label is not None else ""
    name += ".cfg"
    return name