Duration of an FX5 is up to 18 hours. For expedition caving, long trips, and because of the nice diffuse light, many cavers use a carbide lamp. This is a belt mounted 'generator' and a helmet mounted jet,connected by a plastic tube. The generator base contains calcium carbide, and the top contains water. A valve allows water to drip on the carbide, which gives off aceteline.
Most systems have an electric backup, for when the flame goes out.
Many cavers prefer carbide , but pollution caused by dumping spent carbide underground has led to it's use being frowned upon in some circles. South Wales in particular has many caves where carbide is banned. Climbing type helmets are popular, with a chin strap to stop it falling off. Many caves contain vertical drops -'pitches'. So, thats the basic equipment.