There weren't many civilian items GIs could take with them into Charlie's Jungle. The Zippo was an exception.

While Zippo never had an official contract with the military, U.S. soldiers insisted on the windproof lighter during the Vietnam War, inscribing them with mottos that they lived and died by.

Even non-smoking soldiers carried Zippos to warm rationed meals and use as mirrors. There are miracle stories of lighters saving lives: lighters used to signal rescue helicopters or shield against enemy bullets. One-dollar Zippos also became instruments on which GIs would engrave and articulate their frustration, fear and fury at the war. See one such collection here.