The E4K is a break from the standard Explorer Series for Nitecore. The power button is in a bulged out area, necessitating the clip be placed to the side. Being slightly recessed even in that bulge, the button needs a good press to turn the light on. Using 4 CREE XP-L2 V6 LEDs in the head powered by an included 5000mAh 21700 battery, the E4K can shoot out 4400 lumens for half an hour. After that, it begins to step down in brightness.

This light is machined from aerospace-grade aluminum alloy, and given a military-grade hard-anodization. This and the knurling on the body make using it in bare hands kinder to the skin than a smoother form.

Features:

• Manufacturer's page: Nitecore E4K
• Utilizes 4x CREE XP-L2 V6 LEDs
• Optical system combined with crystal coating and PDOT
• Highly efficient constant current circuit
• One side-switch specially designed for outdoors applications controls 5 brightness levels and 3 special modes
• Strobe mode uses randomized frequencies for stronger dizzying effects
• Power indicator under side-switch displays remaining battery power and voltage
• Incorporated ATR module
• Electronic reverse polarity protection
• Optical lens has double-sided scratch resistant coating
• Constructed from aerospace-grade aluminum alloy
• HAIII military-grade hard-anodization
• Waterproof to IP68
• Tailstand capable

Specifications:

• Output modes:
  Turbo: 4400 lumens/30min*; 211m; 11100cd
  High: 1050 lumens/3hr 15min; 105m; 2800cd
  Mid: 320 lumens/7hr 30min; 57m; 810cd
  Low: 50 lumens/45hr; 21m; 110cd
  Ultralow: 2 lumens/700hr; 3m; 3cd
  Strobe
  SOS
  Beacon
  
• IP Rating: 68, dustproof/waterproof to -2m
• Impact resistance: 1m
• LED: 4x CREE XP-L2 V6
  
• Battery: 2x CR123, 2x RCR123, 1x 21700 (included)
  
• Dimensions:
  Length: 117.56mm/4.62in.
  Head Size: 28.6mm/1.13in.
• Weight: 80g/2.82oz

* = Turbo runtime is tested by Nitecore without temperature regulation, actual runtime may vary depending on outside factors