Agri-Farm Products Outdoor Mineral Holder, AFP-132. Holds stones up to 10.2″ / 24cm. This covered mineral holder features a lid that prevents rain from falling directly on the stone. The holder can be mounted on an untreated post or a tree. It effectively protects the mineral stone against hard rain, but also against sunshine. Moreover, there are holes in the base of the holder which allows the salt and mineral-rich liquid to simply run down the untreated holder or post. The animals then lick the post to benefit from the salt and minerals. Ideal for calves, cattle, horse, goat and sheep.