Bilateral safeguard measures limited in duration, suspend concessions only as necessary, and may be extended upon recommendation. Suspension of concessions or bilateral safeguard measures is limited to the period necessary to prevent or remedy serious injury and to facilitate adjustment. An initial measure shall not exceed two years, but may be extended on the Director General's recommendation for up to a further two years, subject to a four year aggregate cap. Measures terminate at the end of an originating good's transition period. Reimposition on a previously subjected originating good is barred for one year after expiry, and any new measure must be shorter than the prior one.