Which of these popular consumer products was originally developed during WWII specifically for military use before becoming a massive retail success?

During and after major military conflicts, surplus military equipment has spawned entire retail industries and product categories we now take for granted. Military necessity often drives innovation, and when these technologies transition to civilian use, they transform consumer markets. This poll explores how a famous military product development eventually revolutionized civilian retail markets in unexpected ways.

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Jeep vehicles (Willys MB)
Aerosol spray cans (developed for insecticide delivery to troops in the Pacific)
Ray-Ban aviator sunglasses (for US Army Air Forces pilots)
Duct tape (originally called 'duck tape' for waterproofing ammunition cases)