61 STAT.] 8OTH CONG. , 1ST SESS.-CH. 120-JUNE 23, 1947 "(4) continues in full force and effect, without resorting to strike or lock-out, all the terms and conditions of the existing contract for a period of sixty days after such notice is given or until the expiration date of such contract, whichever occurs later: The duties imposed upon employers, employees, and labor organizations by paragraphs (2), (3), and (4) shall become inapplicable upon an intervening certification of the Board, under which the labor organiza- tion or individual, which is a party to the contract, has been superseded as or ceased to be the representative of the employees subject to the provisions of section 9 (a), and the duties so imposed shall not be construed as requiring either party to discuss or agree to any modifica- tion of the terms and conditions contained in a contract for a fixed period, if such modification is to become effective before such terms and conditions can be reopened under the provisions of the contract. Any employee who engages in a strike within the sixty-day period specified in this subsection shall lose his status as an employee of the employer engaged in the particular labor dispute, for the purposes of sections 8, 9, and 10 of this Act, as amended, but such loss of status for such employee shall terminate if and when he is reemployed by such employer. "REPRESENTATIVES AND ELECTIONS "SEC. 9. (a) Representatives designated or selected for the purposes of collective bargaining by the majority of the employees in a unit appropriate for such purposes, shall be the exclusive representatives of all the employees in such unit for the purposes of collective bargaining in respect to rates of pay, wages, hours of employment or other condi- tions of employment: Provided, That any individual employee or a group of employees shall have the right at any time to present griev- ances to their employer and to have such grievances adjusted, without the intervention of the bargaining representative, as long as the adjust- ment is not inconsistent with the terms of a collective-bargaining contract or agreement then in effect: Providedfurther, That the bar- gaining representative has been given opportunity to be present at such adjustment. "(b) The Board shall decide in each case whether, in order to assure to employees the fullest freedom in exercising the rights guaranteed by this Act the unit appropriate for the purposes of collective bar- gaining shail be the employer unit, craft unit, plant unit, or subdivision thereof: Provided, That the Board shall not (1) decide that any unit is appropriate for such purposes if such unit includes both professional employees and employees who are not professional employees unless a majority of such professional employees vote for inclusion in such unit; or (2) decide that any craft unit is inappropriate for such purposes on the ground that a different unit has been established by a prior Board determination, unless a majority of the employees in the proposed craft unit vote against separate representation or (3) decide that any unit is appropriate for such purposes if it includes, together with other employees, any individual employed as a guard to enforce against employees and other persons rules to protect property of the employer or to protect the safety of persons on the employer's premises; but no labor organization shall be certified as the representative of employees in a bargaining unit of guards if such organization admits to membership, or is affiliated directly or indirectly with an organiza- tion which admits to membership, employees other than guards. 143 Intervening certifi- cation of Board. Loss of status by employee. Decision of Board rogardlng appropriate unit.