Exhibit 31.1


                            CERTIFICATION PURSUANT TO
                                RULE 15d-14(a) OF
                       THE SECURITIES EXCHANGE ACT OF 1934
                             AS ADOPTED PURSUANT TO
                  SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002


I, Michael A. McLain., certify that:

1. I have reviewed this quarterly report on Form 10-Q of Aearo Company I;

2. Based on my  knowledge,  this  quarterly  report  does not contain any untrue
   statement of a material fact or omit to state a material fact  necessary to
   make the statements made, in light of the  circumstances  under which such
   statements were made, not  misleading  with respect to the period covered by
   this quarterly report;

3. Based on my knowledge, the financial statements, and other financial
   information included in this quarterly report, fairly present in all
   material respects the financial condition, results of operations, and cash
   flows of the registrant as of, and for, the periods presented in this
   quarterly report;

4. The registrant's other certifying officers and I are responsible for
   establishing and maintaining disclosure controls and procedures (as
   defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant and
   we have:

     a)  designed  such  disclosure  controls  and  procedures,  or caused  such
     disclosure controls and procedures to be designed under our supervision, to
     ensure that material  information  relating to the registrant is made known
     to us by others within those  entities,  particularly  during the period in
     which this quarterly report is being prepared;

     b) evaluated the effectiveness of the registrant's disclosure controls and
     procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of the end of
     the period covered by this report based on such evaluation; and

     c) disclosed in this report any change in the registrant's internal control
     over financial reporting that occurred during the registrant's most recent
     fiscal quarter that has materially affected, or is reasonably likely to
     materially affect, the registrant's internal control over financial
     reporting;

5. The registrant's other certifying officers and I have disclosed, based on
   our most recent evaluation of internal control over financial reporting, to
   the registrant's auditors and the audit committee of the registrant's board
   of directors (or persons performing the equivalent function):

      a) all significant deficiencies and material weaknesses in the design or
      operation of internal control over financial reporting which are
      reasonably likely to adversely affect the registrant's ability to record,
      process, summarize and report financial information; and

      b) any fraud, whether or not material, that involves management or other
      employees who have a significant role in the registrant's internal control
      over financial reporting.


Date: August 16, 2004                         /s/ Michael A. McLain
                                                 ---------------------
                                                  Michael A. McLain
                                                  Chairman, President and
                                                  Chief Executive Officer