That's a good question, and I thought about it for a moment. But Digitec would be cutting itself off because of the extra work. And if the product is defective, you as a customer have a simple warranty process anyway.
Here is some more information:
Xtorm Solar Booster 21W. Battery technology: Lithium-ion (Li-Ion), Battery capacity: 10000 mAh, Charging source: Solar. Port 1 power output: 18 W, Port 2 power output: 18 W, Port 3 power output: 18 W.