This is a leather seal gasket applied to almost all Coleman stoves and lanterns. Leather has a longer lifespan than rubber, making it semi-permanent, and it provides a good pumping feel. In particular, the thinner the leather, the higher the quality.
The "2 set of Pump Leather Seal packing Coleman Stove & Lantern" product would be best suited for outdoor adventurers, backpackers, or campers in need of reliable and compact lighting solutions while cooking.
