N.J. Stat. Ann. § 43:13-24

In all cities of the fourth class any member of the life guard force, whether employed as an officer or a guard, who has or shall have served on such force for a period of twenty years, and shall have attained the age of forty-five years, and for a period of ten years preceding his application has been continuously in such service, may, either by the governing body of any such city or upon his own application, be retired upon half pay.