Oh wow. About to get some unwelcome publicity. Nat
http://india.blogs.nytimes.com/2013/04/17/what-are-pressure-cooker-bombs-and -why-do-terrorists-use-them/ >Forensic experts described the pressure cookers used in the Boston marathon blasts as generic, but noted the marking "6L," indicating six liters. Pressure cookers in the United States are <http://www.walmart.com/ip/Presto-6-Quart-Stainless-Pressure-Cooker/5913466> most often measured in quarts, not liters.
