The SOG knife was designed for, and issued to, covert Studies and Observation Group personnel during the Vietnam War. It was unmarked and supposedly untraceable to country of origin or manufacture in order to maintain plausible deniability of covert operators in the event of their death or capture. A chrome-moly steel known as SKS-3 was chosen for the blade and hardened to Rockwell hardness. The blade pattern featured a convex false edge on the clip point of a Bowie knife. The blade was typically blackened to reduce glare. This was done so by applying a dark gun-blue finish (similar to those used on guns) on this carbon steel knife.

There are different designs of SOG pocket knives. Below are just a few examples:~Seven Inch Recon–One of 1300 seven inch knives provided by the Counter Insurgency Support Office (CISO) early in the war. Both the knife and sheath are unmarked.~Seven Inch Recon made by Japan Sword and so marked on the ricasso. It has a blue blade and comes with the original scabbard. Only a couple of these are known to exist.~Fat Guard SOG knife—The first of the 6″ SOG knives. It has a blue blade and brass fittings. It comes with original scabbard. Both the knife and sheath are unmarked.