Reusable grenades were improved by Scott Frank to emulate the fragmentation of a real grenade in war games and scenarios. The grenade can be loaded with paint or pellets. It uses a quick release of highly pressurized gas to break the shell and quickly disperse pellets or paint in all directions. Frank's grenade, although not the first, aimed to be as realistic and predictable as an actual grenade. He developed a more accurate timing mechanism and secondary safety mechanisms to prevent accidental discharge. Both marking rounds and reusable grenades gave airsoft the edge it needed to enter into military and law enforcement training grounds.