def merge_ar_ssfr(ar_df, ssfr_mosdef_merge_no_dups):
    """Merges the ar_df with the ssfr_mosdef_merge_no_dups dataframe

    Parameters:

    Returns:
    ar_ssfr_merge (pd.DataFrame): Pandas dataframe of the ssfr info, mosdef_df info, and duplicates removed
    """
    ar_ssfr_merge = ar_df.merge(ssfr_mosdef_merge_no_dups, how='left', left_on=[
                                'field', 'v4id'], right_on=['FIELD_STR', 'V4ID'])
    return ar_ssfr_merge