CGA Fitting Reference. A CGA fitting is the standardized system for the attachment of a compressed gas cylinder to the required regulator or transfer line. Examples of CGA fittings would be CGA-580 for Non-flamable, Non-oxidizing gasses such as Nitrogen, Argon, or Helium. CGA-590 is used for compressed air and CGA-326 is used for Nitrous Oxide.
Google Authenticator is a mobile security application based on two-factor authentication (2FA) that helps to verify user identities before granting them access to websites and services.
The codes in authenticator apps sync across your accounts, so you can scan a QR code on a phone, and get your six-digit access code on your browser, if supported. Here's a video Google made about 2-Step Verification basics a couple years ago. It will give you a good idea of what's involved.