Salt is the only food (with water) for which animal have a specific appetite, meaning they are able to adapt their consumption to their needs; therefore, nothing is wasted (no over- or under-consumption) and nothing is lost, because the salt is compacted. 
As their need for salt is continuous, SEL’PUR SALINS must be free fed in sufficient quantity all year around, either in stalls or in pastures. 
Cylindrical block with central hole.
Composition: 100% sodium chloride, so 39.3% of sodium