Section 133. Pursuant to this chapter, and notwithstanding the provisions of any general or special law to the contrary, the appointment and reappointment of full-time police officers "and/or firefighter(s)" not subject to the provisions of chapter thirty-one shall be subject to the following provisions:

(a) The initial appointment shall be for a period of one year during which a person shall actually perform the duties of such position on a full-time basis. The initial appointment shall be a probationary period during which police officers "and/or firefighter(s)" shall be deemed employees at will whose removal or dismissal shall be without recourse at any time during such initial appointment.

(b) Appointment subsequent to the initial appointment shall be made annually or for a term of years not exceeding three years, as the appointing authority shall determine, and such appointing authority may remove any such officer for "just" cause, and after a hearing, at any time during such appointment. For police officers "and/or firefighter(s)" covered by collective bargaining agreements which contain standards for the discharge, termination or removal of employees, the nonreappointment of a police officer "and/or firefighter(s)" serving under an appointment subsequent to an initial appointment shall be considered to be a discharge, termination or removal and the standards shall be enforceable with respect to such nonreappointment by the procedures set forth in the collective bargaining agreement.