Ultrafire Battery 3.7 Volt Lithium Ion Ultrafire Lithium Ion Battery LION-1865-30-UF | Zoro
PSA: This is why you should avoid Ultrafire and sketchy Chinese batteries. There's no protection circuit, despite their claim, and their advertised capacity is 9 times what they're capable of. : r/flashlight
UltraFire 18650 Review | DON'T Buy until You See How it Stacks Up
UltraFire 2600mAh 3.7V 18650 Rechargeable BRC Lithium Battery With Pro