29. Supertherm II briquettes, manufactured by Coal Products Limited at Shildon, County Durham, which–
(a)comprise anthracite (as to approximately 36 to 51 per cent of the total weight), petroleum coke (as to approximately 40 to 55 per cent of the total weight) and an organic binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing ;
(c)are unmarked ovoids;
(d)have an average weight of 140 grammes per briquette; and
(e)have a sulphur content not exceeding 2 per cent of the total weight.