TDI LAW ENFORCEMENT KNIFE, PAR In extreme close quarters encounters where a suspect is attempting to take an officer's handgun, or an officer cannot access his handgun, the TDI knife is available as a "last option" knife. When worn on the pant belt the entire unit - knife and sheath - is well concealed. Designed by John Benner, founder and owner of Tactical Defense Institute. Now available with partially serrated blade, coyote brown handle and sheath, and black metal belt clip.