The design of these heating pads is unique and practical. They are made with a mesh of Polyester filament and Micro Metal Conductive Fiber, folded into a protective Polyimide Film. This results in a low-power, flexible pad that draws minimal power, making it an excellent choice for heated garments such as hand-warmers. With the addition of a microcontroller and some sensors, it's even possible to create a climate-controlled hoodie.
Key features of the Sparkfun Heating Pad include an operating voltage of 5V DC, an operating current of approximately 750mA (~6.5Ω), and dimensions of 5 x 10 cm.
For further information on the product, Sparkfun provides a Warmup Profile document and a Hand Warmer Blanket Tutorial. These resources offer valuable insights into the product's functionality and potential applications.