Excise exemption for acrylic fibre waste limits duty liability by capping the leviable excise per unit weight. Exempts wastes of acrylic staple fibre and tow, including tops, falling under the tariff classification for acrylic fibres from central excise duty to the extent the duty exceeds a specified per kilogram cap, using executive authority to limit the leviable excise on those goods to a capped amount per unit weight.