The Go System Bayonet Butane Gas Cartridges are filled with a premium Butane / Propane mix for efficient and effective burning to minus 20 degrees.Bayonet cartridge of premium butane gas for use with our Dynasty family camping series.TinBayonet cartridge.A Countersunk Relief Valve (CRV) system safely releases gas in the case of a build-up in internal pressure.227g Butane-IsoButane Propane Mix Bayonet Gas CartridgeEffective to -20 deg CNon- refillableFilled to the European standard EN417Sold in packs of 4