Thick wall Quick Disconnects are used when the body will be soldered to the vacuum system. Couplings are used to connect a single (glass or metal) tube to your vacuum system. Unions are used to join two (glass or metal) tubes together. Quick Disconnects use Buna-N® or Viton® seals. A&N manufactures the body, plug, and retaining ring of Thick Wall Quick Disconnects from 304 Stainless Steel or Brass. The nut is manufactured from 303 Stainless Steel or Brass.