Tourist gas OPTIMUS. The high calorific gas, which is a mixture of propane, i-butane and n-butane, allows the stove to be used even in very adverse weather conditions. Cartouche is equipped with a screw-on threaded socket. The cartridge meets the European safety standard EN521 and EN417. The valve is equipped with a system to prevent accidental gas leakage. The plastic cover protects the valve against damage.