The U.S. Justice Department's National Institute of Justice (NIJ) began studying "smart gun" technologies several years ago. The most promising technology involved the use of a radio frequency to verify the identity of the user. Simultaneously, Colt's Manufacturing was exploring similar technology that involved verification by radio frequency. In its endeavors, Colt's own investment was supplemented with $500,000 of NIJ funding. By early 1998, Colt's had a proof-of-concept device that was demonstrated to a group of law enforcement and corrections officials, with feedback from participants on what did and did not work with the prototype. This led to the development and testing of a second-generation smart gun, which was delivered to NIJ for a controlled field testing program in late 1998. This second-generation prototype emits a radio signal that is received by a small wrist transponder worn by the user. The wrist transmitter receives the information and returns a coded radio signal, which prompts the removal of a blocking pin within the gun's trigger mechanism, enabling the gun to fire. Among the other safety factors in this prototype are user verification within the time required to draw and aim a gun; a required distance of 8 inches or less between the gun and the transponder before the gun will fire; and indicators visible only to the user that shows the enabled or disabled status of the gun; a fail-safe override that automatically arms the weapon if the electronics fails; and support for multiple users on the same frequency, which enables a full squad or a small department to use the same band.