Always keep a spare! Shooting airguns is fun and it's always better to have a spare loaded up and ready to go. Shooters who have picked up the officially licensed GLOCK G17 Gen 5 pellet pistol can use this magazine to keep the pellets flying. Like the factory magazine included with the G17 Gen 5, this magazine holds 21 .177 caliber pellets and a single 12 gram non-threaded CO2. Be sure to pick up a few spares to keep shootin! Officially Licensed Product of GLOCK™.