Microtech LUDT 135-5 OD Automatic Knife Olive Drab SERRATED. The Microtech LUDT Automatic Knife is overall open length 8 inches, this automatic Microtech L-UDT knife has a 3.375 inch blade that is .13 inches thick. It has an aluminum handle, is tip up carry and is MADE IN THE USA! The UDT was introduced by Anthony Marfione a little over 20 years ago as the U.D.T. (Underwater Demolition Team) and soon after the Large (LUDT) was introduced.