Keep spares ready with this 5-pack of 8g non-threaded CO2 cartridges-designed to power HDP 50 Compact personal-defense devices and training sessions. Each cartridge delivers consistent, reliable gas output and stores indefinitely when kept cool and dry. For smooth installation and extended valve life, place a drop of silicone oil on the cartridge tip before seating. Pack of five cartridges, non-food grade CO2, compatible with HDP 50 Compact; manufactured by Umarex USA, Inc.