Which of these military-related product designs was originally created for troops in WWII before becoming a massive civilian retail success with virtually unchanged packaging?

Throughout military history, recruiting campaigns and military equipment branding have utilized sophisticated marketing techniques. From ancient symbols on shields to modern recruitment campaigns, military forces have employed distinctive visual identities and persuasive messaging. This trivia question explores how a famous World War II product design influenced consumer psychology and became an enduring brand icon.

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M&Ms candy (designed to allow soldiers to carry chocolate that 'melts in your mouth, not in your hands' in various climates)
Ray-Ban Aviator sunglasses (designed for pilots but marketed to civilians with the same military mystique)
Jeep vehicles (designed as military transport with the same boxy, rugged design later marketed to civilians)
Swiss Army Knife (designed for soldiers with the same red cross emblem later becoming its civilian brand identity)