Rubber Conveyor belts falls into two categories, 1.) Light weight Application belts Light weight belts are usually used in Paper conveying, Folder gluers, etc. These belts range from 1 mm to 6 mm thickness. 2.) Heavy duty Application belts. Heavy duty belts are usually used for heavy industries like Mining, Quarries, Cement, Fertilizers, etc. These belts range from 4 mm to 15 mm thickness.