8.4V Battery Mobile Power 4 x 18650 Waterproof Battery Pack Case with DC and USB Interface Strap for Bike Light Headlamp Mobile Phone

Features:
Portable battery mobile power, suitable for 3.7V 18650 rechargeable battery. (Batteries are not included in the delivery.)
The DC interface supports 8.4V input and output. The USB interface can charge the mobile phones.
No need to spot welding the battery, which reduces the internal resistance of the battery and improves the battery discharge performance and battery lifespan.
Supports protection functions such as overcharge, overdischarge, and overcurrent. With 3-level power display, real-time monitoring of battery power.
Waterproof design, it can be used normally even in severe weather such as rain and snow, with reliable quality and safer.
With nylon straps, it is convenient to fix on the bicycle, which is very suitable for cycling enthusiasts.