FORM OF 8.875% SENIOR NOTE

Exhibit 4.3

FORM OF 8.875% SENIOR NOTE

(Face of Note)

8.875% Senior Notes due 2019

OLIN CORPORATION

8.875 % SENIOR NOTES DUE 2019

Olin Corporation promises to pay to Cede & Co., or registered assigns, the principal sum of               Dollars ($          ) on August 15, 2019.

Interest Payment Dates:  February 15 and August 15, beginning

Record Dates:  February 1 and August 1

Reference is made to further provisions of this Note set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as set forth at this place.

Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual signature, this Note shall not be entitled to any benefits under the Indenture referred to on the reverse hereof or be valid or obligatory for any purpose.

In WITNESS HEREOF, the Company has caused this instrument to be duly executed.

Dated:

TRUSTEE’S CERTIFICATE OF AUTHENTICATION

This is one of the Notes

referred to in the within-mentioned Indenture:

Dated:

(Reverse of Note)

8.875% Senior Notes due 2019

OLIN CORPORATION

Capitalized terms used herein shall have the meanings assigned to them in the Indenture referred to below unless otherwise indicated.

(1)            Interest .  Olin Corporation, a Virginia corporation, or its successor (together, “ Olin ”), promises to pay interest on the principal amount of this Note (the “ Notes ”) at a fixed rate of 8.875% per annum.  Olin will pay interest in United States dollars (except as otherwise provided herein) semiannually in arrears on February 15 and August 15 of each year, commencing on February 15, 2010 or, if any such day is not a Business Day, on the next succeeding Business Day (each an “ Interest Payment Date ”).  Interest on the Notes shall accrue from the most recent date to which interest has been paid or, if no interest has been paid, from and including August 19, 2009; provided that if there is no existing Default or Event of Default in the payment of interest, and if this Note is authenticated between a record date referred to on the face hereof and the next succeeding Interest Payment Date (but after August 19, 2009), interest shall accrue from such next succeeding Interest Payment Date, except in the case of the original issuance of the Notes, in which case interest shall accrue from the date of authentication.  Olin shall pay interest (including post-petition interest in any proceeding under any Bankruptcy Law) on overdue principal at the rate equal to 1% per annum in excess of the then applicable interest rate on the Notes to the extent lawful; it shall pay interest (including post-petition interest in any proceeding under any Bankruptcy Law) on overdue installments of interest (without regard to any applicable grace period) at the same rate to the extent lawful.  Interest shall be computed on the basis of a 360-day year comprised of twelve 30-day months.  The interest rate on the Notes will in no event be higher than the maximum rate permitted by New York law as the same may be modified by United States law of general application.

(2)            Method of Payment .  Olin will pay interest on the Notes (except defaulted interest) on the applicable Interest Payment Date to the Persons who are registered Holders of the Notes at the close of business on the February 1 and August 1 preceding the Interest Payment Date, even if such Notes are cancelled after such record date and on or before such Interest Payment Date, except as provided in Section 2.4 of the Supplemental Indenture with respect to defaulted interest.  The Notes shall be payable as to principal, premium and interest at the office or agency of Olin maintained for such purpose within or without the City and State of New York, or, at the option of Olin, payment of interest may be made by check mailed to the Holders at their addresses set forth in the register of Holders; provided that payment by wire transfer of immediately available funds shall be required with respect to principal of, premium, if any, and interest on, all Global Notes and all other Notes the Holders of which shall have provided written wire transfer instructions to Olin and the Paying Agent.  Such payment shall be in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts.

Any payments of principal of and interest on this Note prior to Stated Maturity shall be binding upon all future Holders of this Note and of any Note issued upon the registration of transfer hereof or in exchange hereof or in lieu hereof, whether or not noted hereon.  The amount due and payable at the maturity of this Note shall be payable only upon presentation and surrender of this Note at an office of the Trustee or the Trustee’s agent appointed for such purposes.

(3)            Paying Agent and Registrar .  Initially, The Bank of New York Mellon Trust Company, N.A., the Trustee under the Indenture, shall act as Paying Agent and Registrar.  Olin may change any Paying Agent or Registrar without notice to any Holder.  Olin or any of its Restricted Subsidiaries may act in any such capacity.

(4)            Indenture .  Olin issued the Notes under an Indenture, dated as of August 19, 2009 between Olin and the Trustee (the “ Base Indenture ”), as supplemented by the Supplemental Indenture dated August 19, 2009 (the “ Supplemental Indenture ” and, as so supplemented,   the “ Indenture ”), between Olin and the Trustee.  The terms of the Notes include those stated in the Indenture and those made a part of the Indenture by reference to the Trust Indenture Act of 1939, as amended (15 U.S. Code §§ 77aaa-77bbbb) (the “ TIA ”).  To the extent the provisions of this Note are inconsistent with the provisions of the Indenture, the Indenture shall govern.  The Notes are subject to all such terms, and Holders are referred to the Indenture and the TIA for a statement of such terms.  The Notes issued on the Issue Date are senior unsecured obligations of Olin limited to $150,000,000 in aggregate principal amount, plus amounts, if any, sufficient to pay premium and interest on outstanding Notes as set forth in Paragraph 2 hereof.  The Indenture permits the issuance of Additional Notes subject to compliance with certain conditions.

(5)            Optional Redemption .

(i)           The Notes are subject to redemption, at the option of the Company, in whole or in part, at any time on or after August 15, 2014 upon not less than 30 nor more than 60 days’ notice at the following Redemption Prices (expressed as percentages of the principal amount to be redeemed) set forth below, plus accrued and unpaid interest, if any, to, but not including, the redemption date (subject to the right of Holders of record on the relevant regular record date to receive interest due on the relevant interest payment date), if redeemed during the 12-month period beginning on August 15 of the years indicated below:

(ii)&nbs