I accidentally found an incredible solution to my cold fingers from Raynaud’s Disease. The OCOOPA Fast-Charging 10,000mAh back-up battery and handwarmer with PD & QC 3.0 has three temperature settings and heats both sides of its excellent Ergonomic Design: The upper-wide, lower-narrow design is more suitable for grasping than the oval shape fits the natural curve of your palm and is anti-slip. The high-grade silicone oil surface coating is soft and delicate to the touch, and has superior thermal conductivity.

The OCOOPA handwarmer is built to last, with the hottest setting providing a powerful heat that lasts for nearly four hours on high, and more than 12 hours on the lowest setting. This durability ensures that you can rely on the OCOOPA handwarmer for long-lasting warmth, even in the most extreme conditions.

Recharging is super fast; I used an 18W USB wall charger, and charging a completely drained unit took three hours and 12 minutes.

The OCOOPA hand warmer is not just a solution for cold fingers. It's also an excellent power source and backup battery for your mirrorless camera and mobile phone. This versatility empowers you to stay connected and capture your outdoor adventures, all while keeping your hands warm and comfortable.

I now have four of these with me at all times while in the field: one for each loose-fitting mitten and two extra fully charged units as backups in case I accidentally forget to turn off or charge them. On the coldest days, I can use the two extras as heaters in the inside pockets of my parka.