You can buy it in your hobby store.
The DF Models Pro Racing batteries have been completely revised. They shine not only with a new design but also with more power! All batteries are equipped with high quality silicone cables and T-connector. With 45C loadable, the batteries are suitable for almost any RC car. Take off with the new Pro Racing Power from DF Models! All LiPo batteries now in a practical hanging blister.
Safety/ hazard information for rechargeable batteries/ batteries - PDF