g and mailed certified return receipt requested, postage prepaid, or delivered by overnight delivery service: (a) If to Purchaser: Aquilamus GmbH Saarbrucker Strasse 6 10405 Berlin, Germany (b) If to Seller: Lviv Enterprises LLC, 121 East 69th Street, Suite 2, New York, New York 10021 11. WAIVER: The failure