LiitoKala Lii-40A 21700 Battery, 4000mAh, 40A High-Drain

Flat top and unprotected by design, which is what makes it fit vape mods that reject the longer protected cells, and also what makes it suitable for flashlights pushing over 2000 lumens where a protection circuit would throttle the current the light actually needs.

40A max continuous discharge, 4000mAh of genuine measured capacity rather than an inflated label figure. Because there's no protection circuit, it needs a smart charger with auto cut-off and shouldn't be left charging unattended overnight.

Specifications

• 4000mAh (genuine capacity), 40A max discharge
• Flat top, unprotected
• 1000+ charge cycles
• Under 30 milliohms internal resistance

Rated for over 1000 charge cycles, low internal resistance under 30 milliohms. A known, trusted choice among flashlight enthusiasts running Convoy, Sofirn or similar high-drain lights. The Klarus 21700 5000mAh is a protected alternative that's a safer default in a single flagship flashlight.