PETN or Pentaerythritol Tetranitrate is an explosive used in a variety of military and civilian applications. It's primarily found in Primacord, an explosive fuse that looks like clothesline. PETN is not very shock sensitive, and is usually detonated by an explosive blasting cap. Traces of PETN were supposedly found on pieces of TWA flight 800, leading some to suspect that the plane was brought down with a bomb.

PETN is also used as a vasodilator to treat people who have chest pain. It's usually mixed with lactose.