The buyer agrees to purchase from the contractor its sodium hypochlorite solution at a volume concentration of 15 percent available chlorine, to be transport delivered during the period of this contract, subject to the conditions and agreement contained herein. 3. The estimated quantity will be 26,000 - 30,000 gallons per month of solution at a volume concentration of 15 percent available chlorine sodium hypochlorite. 4. The contractor will protect the City against any increase in the price of sodium hypochlorite. 5. Whenever contractor is unable to ship within 48 hours after receipt of order, the City reserves the right to order sodium hypochlorite from another vendor. Any difference in cost shall be charged to the vendor in default.