Any notice, request, approval, consent or written communication required or permitted to be delivered under this Lease shall be: (a) in writing; and (b) transmitted by personal delivery, overnight courier or United States Certified Mail, return receipt requested. Such writings shall be addressed to Landlord or Tenant, as the case may be, at the respective designated addresses set forth opposite their signatures, or at such other address(es) as they may, after the execution date of this Lease, specify by written notice delivered in accordance with this Section 6.1, with copies to the persons at the addresses, if any, designated opposite each party’s signature. Those notices which contain a notice of breach or default or a demand for performance may be sent by any of the methods described in clause (b) above, but if transmitted by personal delivery or electronic means, shall also be sent concurrently by certified or mail, return receipt requested.