comprise anthracite (as to approximately 75% of the total weight), coal and reactive coke (as to approximately 21% of the total weight) and cold-setting resin binder (as to the remaining weight);

were manufactured from those constituents by a process involving extrusion;

are unmarked hexagonal briquettes;

have an average weight of 130 grams; and

have a sulphur content not exceeding 2% of the total weight.