The modern Western alphabet was derived from the Greek alphabet, the central trading and cultural language of the ancient Mediterranean. Now the Greek alphabet is used often in worldwide physics, chemistry, and mathematics, and its letters name certain North American university fraternities and sororities. Tau is the nineteenth letter of the Greek alphabet. Whether you're a scientist or a university student...give a nod to Greek pride with our crisply cast 6mm Tau stamp. This 66x9.5x9.5mm sturdy steel stamp is plated to reduce rust and wear. In order to better prevent rust, our stamp sets are lightly coated with oil. Simply wipe down with a dry paper towel or rag before using. Do not store in damp places.