"Heart" of the lantern and stove.
Consists of (left to right) a tip cleaner rod, a hollow tube, some type of heat-transfer device like paper tube or a spring (not shown) and a gas tip.
Used to heat fuel (convert liquid "gas" to gas vapor) prior to introduction into the lantern/stove air system.
Gas tip is sized according to lantern/stove application.
Most are still available, larger ones can be easily cleaned and re-used.