extension.
At any time prior to the expiration of an eavesdropping or video surveillance warrant, the applicant may apply to the issuing justice, or, if he is unavailable, to another justice, for an order of extension. The period of extension shall be no longer than the justice deems necessary to achieve the purposes for which it was granted and in no event longer than thirty days. The application for an order of extension must conform in all respects to the provisions of section 700.20 and, in addition, must contain a statement setting forth the results thus far obtained from the interception, or a reasonable explanation of the failure to obtain such results. The provisions of sections 700.15 and 700.25 are applicable in the determination of such application. The order of extension must conform in all respects to the provisions of section 700.30. In the execution of such order of extension the provisions of section 700.35 are applicable.