The quality of breeding stock is ensured through the annual Breeding Stock Inspections or Keurings. Horses are evaluated and graded according to quality and to their potential for adding to the breeding pool. For stallions, inspection prior to entry into the studbook is only the first step before becoming a fully approved stallion. The stallion is expected to demonstrate his athleticism through either a 100-day test or through sport. His offspring are also inspected for quality and genetic defects. Only then is he granted a lifetime breeding license. Mares are also inspected and if of sufficient quality are entered into one of three studbooks.