Airlines prefer to hire poised, tactful, and resourceful people who can interact comfortably with strangers and remain calm under duress. Flight attendants must be in excellent health, and have the ability to speak clearly. Airlines usually have age, physical, and appearance requirements. Applicants usually must be at least 18 to 21 years old, although some carriers may have higher minimum-age requirements. Applicants must meet height requirements for reaching overhead bins, which often contain emergency equipment, and most airlines want candidates with weight proportionate to height. Vision is required to be correctable to 20/30 or better with glasses or contact lenses (uncorrected no worse than 20/200). Men must have their hair cut above the collar and be clean shaven. Airlines prefer applicants with no visible tattoos, body piercing, or unusual hairstyles or makeup. In addition to education and training, airlines conduct a thorough background check as required by the FAA, which goes back as many as 10 years. Everything about an applicant is investigated, including date of birth, employment history, criminal record, school records, and gaps in employment. Employment is contingent on a successful background check. An applicant will not be offered a job or will be immediately dismissed if his or her background check shows any discrepancies. All U.S. airlines require that applicants be citizens of the United States or registered aliens with legal rights to obtain employment in the United States