15" Anagram® Diamondz® Foil balloons are multi-sided in a diamond shape. High quality, 15 Inch Diamond shape foil balloon. Manufactured with the highest quality materials, this deluxe 15″ Foil Mylar Balloon comes complete with a built-in, 1-way Helium valve that securely seals in helium as you inflate the balloon. When fully inflated, this balloon measures approx. 15″ in diameter.