https://www.onehealthgiant.com/why-the-voltex-heated-vest-is-a-game-changer-for-outdoor-workers/

The temperature settings on the vest are easily adjustable, allowing users to tailor the level of heat to their preference. Typically, these settings range from low to high heat, so whether you need just a gentle warmth on a cool day or intense heat during an extreme cold spell, the vest adapts. With a simple press of a button, you can toggle between different temperature levels and switch it off when you no longer need warmth.