Excise duty exemption on marble tiles limits payable duty to a specified per square metre rate, reducing excess duty. The Central Government, under sub section (1) of section 5A of the Central Excises and Salt Act, 1944, exempts marble tiles under sub heading No. 2504.31 from excise duty to the extent that such duty exceeds the amount calculated at the rate of Rs. 10.50 per square metre, thereby fixing an effective per unit rate for duty liability.