The Microtech HALO Vi (High Altitude, Low Open) is the first automatic single action, out-the-front (OTF), knife ever produced by Microtech Knives.. The HALO 6, when deployed, provides the absolute tightest lock up possible. When retracted, the knife can be easily concealed in its hand molded kydex carry rig. The one handed, fast action open, has fired its way into the hands of thousands of protective agents. HALOåäÌÝå»s smooth lines, light weight, and deadly edge, provide a little more than just backup.