Degassing Tool, Fits Benjamin Challenger, Discovery, Fortitude and Maximus Air Rifle Degassing tool Removes air or CO2 from the reservoir Fits the Benjamin Challenger, Discovery, Maximus and Gen 1 Fortitude rifles If you need to release air from an overfilled Benjamin Challenger, Discovery, Fortitude, or Maximus rifle, this degassing tool will make the process a snap. Please refer to your air rifle's manual for detailed use instructions.