Specialized "windproof" butane lighters are manufactured for demanding conditions such as shipboard, high altitude, and wet climates. Some dedicated models double as synthetic rope cutters. Such lighters are often far hotter than normal lighters (those that use a "soft flame") and can burn in excess of . The windproof capabilities are not achieved from higher pressure fuel; windproof lighters use the same fuel (butane) as standard lighters, and therefore develop the same vapour pressure. Instead, windproof lighters mix the fuel with air and pass the butane–air mixture through a catalytic coil. An electric spark starts the initial flame, and soon the coil is hot enough to cause the fuel–air mixture to burn on contact.