Garment, shoe and furniture factories often pack thousands of cartons in one run, and every carton needs a desiccant pack. Put an expensive one in all of them and your packaging cost climbs noticeably. Skip it, and shoes, leather, fabric and wood can go moldy right in the warehouse. For dry food, the buyer also asks whether the pack inside the carton is safe.
Clay is a natural clay (bentonite) in 2 to 4mm granules that absorbs about 30 to 35% of its weight at 90% humidity. A pack works steadily across a wide temperature range, from 0 to 50°C and best at 20 to 40°C. The pouch keeps the granules inside so no fibers shed, and the clay does not corrode your goods. Two things to know first: clay absorbs more slowly than silica gel, and once saturated it must be replaced, though for stored cargo or fairly short routes both are usually acceptable.