The Royal Brew Nitro Keg will work with most 2 gram Nitrogen chargers,(2 per 64 oz batch) or most 8 gram Nitrous Oxide N₂O chargers (1 per 64oz batch). If using multiple per batch, let cartridges sit for 20-30 minutes to absorb gas from the 1st cartridge, then add a 2nd cartridge! Nitrogen Cartridges (N₂)that we recommend best for Royal Brew:Click Here. Nitrous Oxide Cartridges (N₂O)that we recommend for Royal Brew:Click Here