FCW Spring Dummy Cartridge 40MM Grenade Cartrige Metal Base Type
 
Can shoot with ANY of Airsoft / BB Gel Grenade Launcher
Spring power source and no need gas injection 
Video:  https://youtube.com/shorts/ruDKIoSYeZ8?si=QLOmw7YxFg3vmh3j
 
FCW Spring 40MM Grenade Cartrige Plastic Base Type
 
Can shoot with ANY of Airsoft / BB Gel Grenade Launcher
Spring power source and no need gas injection