Exhibit 10.5

TAX SHARING AGREEMENT

THIS AGREEMENT (this “ Agreement ”) made and entered into as of May 13, 2004, by and among PP Holding Corporation II, a Delaware corporation (“ PHC II ”), PP Holding Corporation, a Delaware corporation and direct wholly owned subsidiary of PHC II (“ PHC ”), Polypore, Inc., a Delaware corporation and direct wholly owned subsidiary of PHC (“ Polypore ”), and such direct and indirect subsidiaries of PHC II that are listed on Exhibit A hereto from time to time (collectively with PHC and Polypore, the “ Subsidiaries ” and each individually, a “ Subsidiary ”).

WITNESSETH:

WHEREAS, PHC II and each of the Subsidiaries qualifies as an “includible corporation” within the meaning of Section 1504(b) of the Internal Revenue Code of 1986, as amended (the “ Code ”);

WHEREAS, the affiliated group of corporations, consisting of PHC II, as the common parent, and each of the Subsidiaries (the “ Polypore Group ”), qualifies as an “affiliated group” within the meaning of Section 1504(a) of the Code; and

WHEREAS, the Polypore Group desires to take advantage of the tax savings that may result from the filing of U.S. federal income tax returns on a consolidated basis, in accordance with Sections 1501 et seq . of the Code and the Treasury Regulations promulgated thereunder.

NOW, THEREFORE, in consideration of the covenants, agreements, terms and conditions contained herein, and for other good, valid and binding consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto, intending to be legally bound, hereby agree as follows:

SECTION 1.  Defined Terms .  As used in this Agreement, the following terms shall have the following meanings.

“ Code ” shall have the meaning set forth in the recitals of this Agreement.

“ Fiscal Year ” shall mean the annual accounting period of PHC II and any other Member.

“ Interim Payments ” shall have the meaning set forth in Section 3(b) of this Agreement.

“ Member ” shall mean a member (as defined in Treasury Regulations Section 1.1502-1(b)) of the Polypore Group.

“ PHC ” shall have the meaning set forth in the heading of this Agreement.

“ PHC II ” shall have the meaning set forth in the heading of this Agreement.

“ Polypore ” shall have the meaning set forth in the heading of this Agreement.

“ Polypore Group ” shall have the meaning set forth in the recitals of this Agreement.

“ Separate Return Liability ” shall mean, with respect to any Subsidiary for any Fiscal Year, the U.S. federal income taxes (including any minimum tax or alternative minimum tax) that would be payable by such Subsidiary to the U.S. Treasury had the Subsidiary filed a separate income tax return for that Fiscal Year based on the Subsidiary’s Separate Taxable Income for that Fiscal Year.

“ Separate Taxable Income ” shall mean, with respect to any Subsidiary for any Fiscal Year, the income, gains, losses, deductions and credits of such Subsidiary for that Fiscal Year calculated as follows:  (i) any dividends received by one Member from another Member will be assumed to qualify for the 100% dividends received deduction of Section 243 of the Code or shall otherwise be eliminated from such calculation; (ii) gain or loss on intercompany transactions, whether or not deferred, shall be treated by each Member in the manner required by Treasury Regulations Section 1.1502-13; (iii) limitations on the calculation of a deduction or the utilization of tax credits or the calculation of a tax liability shall be made on a consolidated basis; (iv) net operating losses and credits of a Subsidiary shall be treated as available to such Subsidiary in determining such Subsidiary’s Separate Taxable Income, and shall not be reduced even if such net operating losses or credits are used in determining the consolidated taxable income of the Polypore Group, instead, such net operating losses and credits shall be reduced only if, when and to the extent used in determining the Separate Taxable Income of the Subsidiary; and (v) elections relating to tax credits and tax computations that differ from the consolidated treatment if separate returns were filed shall be made on an annual basis by PHC II.

“ Subsidiary ” and “ Subsidiaries ” shall have the meanings set forth in the heading of this Agreement.

SECTION 2.  Consent to Filing of Consolidated Return .

(a)           PHC II shall file a consolidated U.S. federal income tax return, and pay to the U.S. Treasury any taxes due thereon, on behalf of the Polypore Group for the taxable year ending December 31, 2004, and for each subsequent taxable period for which this Agreement is in effect and for which the Polypore Group is required or permitted to file a consolidated tax return; provided , that PHC II shall not be liable for any taxes attributable to a Subsidiary if such Subsidiary has not complied with its tax payment requirements as set forth in Section 3 hereof.  Each Subsidiary shall execute and file such consents, elections and other documents that may be required or appropriate for the proper filing of such returns.

(b)           Each corporation that, subse