Customs duty amendment: revised exemption quantity and differentiated duty rates for specified rubber import tariff items. Amendment to Notification No.21/2002 adds a proviso permitting goods specified at new serial 491B to qualify under the notification if imported by the stated cut-off date, and inserts entries 491A and 491B in the Table: 491A grants a limited aggregate exemption for specified tariff items subject to a concessional duty rate for the remainder of the financial year; 491B applies to all other imports of those items and prescribes a differentiated duty rate mechanism.