From a Los Angeles estate, New Old Stock used for display only.  An engraved metal titling is affixed to both sides.  The tokens fit into their slots snugly but they may pop out during transit; this is not a defect -- they're easily refitted.

Per an online overview:

The TWA "Milestones in Manned Flight" set is a 1969 collection of six commemmorative silver-colored tokens (approximately 1.5 inches in diameter) celebrating aviation history.  

Key Details of the TWA Token Collection:

Release Year: 1969.

• Issuer: Trans World Airlines (TWA).
• Set Composition: Usually a 6-medallion set, often found in a two-sided, blue or wood-colored display frame.
• Individual Tokens/Subjects:
  • Leonardo da Vinci (1490): Concept of manned flight.
  • Montgolfier Brothers (1783): First hot air balloon ascent.
  • Wright Brothers (1903): First powered flight.
  • Amelia Earhart: Solo transatlantic flight.
  • Charles Lindbergh (1927): First solo transatlantic flight.
  • Apollo 11 Crew (1969): First moon landing.