Airtight Seal is an enchantment added by Advanced Rocketry. It can be applied to all equipment and allows the player to breathe in space. The oxygen bar can be filled by standing on a Gas Charge Pad. To apply the enchantment the equipment must be fed into the Chemical Reactor. You can attain this by placing a Helmet, Leggings, or Boots in the Input Hatch of the Chemical Reactor with a diamond. For a chestplate, you will need a diamond and a Super High Pressure Tank to enchant it with Airtight Seal.