1. Outdoor products must be waterproof, and meet an IPX5 rating (all-weather), meaning they can withstand heavy rain or accidental splashes of water on vital areas.
2. Outdoor heating must be achieved through thermal radiation. In the outdoors, which is not a sealed space, it's difficult to heat the body through convection and heat conduction. Attempting to heat oneself in moving air is unscientific, akin to drinking poison to quench thirst-it pollutes the environment and wastes resources.
3. Heating methods should be ergonomic, heating the torso from the ankles up, rather than heating the head vertically from top to bottom.