Exhibit
  31.1

CERTIFICATION
  PURSUANT TO
  RULE 15d-14(a) OFTHE
  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 annual report on Form 10-K of Aearo Company I;                                                    
|-- | -----------------------------------------------------------------------------------------------------------------------------
|   |                                                                                                                              
|2. | Based
      on my knowledge, this annual 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 annual report;              
|   |                                                                                                                              
|3. | Based
      on my knowledge, the financial statements, and other financial information
      included in this annual         
|   | 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 annual 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-15(e) and 15d-15(e))
      for the registrant and        
|   | we
      have:                                                                                                               
|   |                                                                                                                              
|   | a)                                                                                                                           
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|   | b)                                                                                                                           
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|   | c)                                                                                                                           
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|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)                                                                                                                           
|   |                                                                                                                              
|   |                                                                                                                              
|   |                                                                                                                              
|   | b)                                                                                                                           
|   |                                                                                                                              
|   |                                                                                                                              

|                             | /s/
      Michael A. McLain                  
|---------------------------- | ---------------------------------------------
|                             |                                              
|                             | Michael
      A. McLain                      
|                             | Chairman,
      President and Chief Executive
|                             | Officer                                      
|                             |                                              
|Date:December
      17, 2004 |                                              

---