A computer, powerbank or other device with a USB port or a USB power adapter.
Plug the USB charging cable into a power adaptor or computer. Then place your phone on the charger and it will start charging.
When purchasing a product made out of bamboo you not only purchase a natural, biodegradable product. You also support the growth of a plant that produces oxygen, reduces carbon dioxide in the air, has a low environmental footprint when produced, prevents drouth and creates jobs in developing countries.