Mossy Oak BioLogic BioRock is 100% natural mineral supplement. In its natural form, it is not a compressed mineral lick. Lasts much longer than a typical salt lick. Contains over 84 minerals including ones believed to promote deer health and antler growth. Key minerals include: calcium, phosphorus, magnesium and sulfur. Slowly dissolves into the soil to create long lasting, frequently visited "deer lick". Check your local laws and regulations before using BioLogic products.