product or service is substantial. (ii) Grade B The Task Force concludes that the current evidence is sufficient to assess the balance of benefits and risks of the product or service, and, on the basis of such evidence, recommends the product or service and determines that there is high certainty that the net benefit of the product or service is moderate or there is moderate certainty that the net benefit of the product or service is moderate to substantial. (iii) Grade C The Task Force concludes that the current evidence is sufficient to assess the balance of benefits and risks of the product or service, and, on the basis of such evidence, does not make a recommendation of the product or service and clinicians may provide this product or service to selected patients depending on individual circumstances. However, for most individuals without signs or symptoms there is likely to be only a small benefit from this product or service. (iv) Grade D The Task Force concludes that the current evidence is sufficient to assess the balance of benefits and risks of the product or service, and, on the basis of such evidence, recommends against the product or service and determines that there is moderate or high certainty that the product or service has no net benefit or that the harm of the product or service outweighs the benefits. (v) Grade I The Task Force concludes that the current evidence is not sufficient to assess the balance of benefits and risks of the product or service. (E) Changes in grading system (i) In general The Director may provide, by regulation, for changes in the grading system described in subparagraph (D). (ii) Impact of changes If the Director makes a change in the grading system under clause (i) for a particular grade, the Task Force shall review and regrade the services previously classified within that grade. Such review and regrade may be done through an expedited process but any such change in grade shall not take effect before such review process is completed.