Duty expression amendment: specifies per tonne measurement for the Central Excise tariff item, clarifying levy basis. Corrects the duty wording in item II(iii)(b) of Notification No. 4/2011 Central Excise (1 March 2011) by replacing '10%+ Rs. 160' with '10%+ Rs. 160 per tonne', thereby specifying that the additional fixed component of the duty is to be levied on a per tonne basis and clarifying the basis for assessment and compliance.