N.J. Stat. § 43:17-9
43:17-9. The membership of such corporation shall consist, without any formal election thereto, of the officers and members of such fire engine, hook and ladder, hose and supply company or companies, fire association or fire department, or board of firewardens, as shall be under the supervision or control of the governing board or body of the municipality or fire district and who, at the time of their becoming eligible for membership in the New Jersey State Firemen's Association, shall be not less than 18 years of age and who were not more than 57 years of age at the time of joining the New Jersey State Firemen's Association and shall furnish evidence of good health in accordance with such reasonable rules and regulations as the executive committee of the New Jersey State Firemen's Association shall from time to time establish; the officers and members of any nonprofit corporations and associations incorporated pursuant to N.J.S. 15A:1-1 et seq.; and the officers and members of any association therein of exempt firemen. The whole body of the membership of such corporation shall have the same rights therein as the charter members thereof.
N.J.S. § 43:17-9