These Lithium-ion polymer (Lipo) battery of Petzl has a lot of power, low self-discharge, low internal resistance. Can be charged quickly and is a lightweight. Petzl manufactures very qualitative, innovative headlamps. Wearing a headlamp on your head is very practical and common today. 30 years ago (Petlz invention) is was not. Since then, Petzls have become increasingly light, compact, durable and powerful.