Astrolux S43 LH351D flashlight review

4 x Samsung LH351D LEDs
4000 lm output
8464 cd intensity
1 x 18650 Li-Ion battery

The Astrolux S43 LH351D flashlight released in 2018. It uses 4 x Samsung LH351D LEDs, TIR reflector and 1 x 18650 Li-Ion battery. The powerful emitter in this flashlight provides up to 4000 lm output, 8464 cd intensity, and a beam distance of 184 m.

Wondering if the Astrolux's flashlight is a must-have? Keep reading to find out!

Table of Contents

The content of this article reflects our own experiences and viewpoints. We aim to offer insights on a topic, and we hope others find it helpful and motivating. Additionally, we make every effort to provide accurate and comprehensive coverage. If you found an error or something lacking in the specifications for the Astrolux S43 LH351D, then tell us.

Astrolux S43 LH351D / S43LH351D

The S43 LH351D is a powerful and reliable flashlight. It has impressive illumination and durable construction. It is an exceptional lighting tool, it works in many situations and environments. TIR lens plays a significant role in shaping the beam pattern of the S43 LH351D flashlight. The S43 LH351D's mode memory makes the user experience more seamless and intuitive. It has a strobe function, which is one of the most effective self defense tools available. This USB rechargeable flashlight has become popular. It's a top choice for both everyday and demanding use.

Astrolux S43 LH351D specifications

NameS43 LH351D
Rated 4 / 5 based on 1429 user votes.

Flashlights let you navigate in the dark. They help you find supplies and signal for help. They also provide comfort and security in tough times.

Astrolux S43 LH351D / 1

Body, materials, weight, colors

Weight60 g
Length88.7 mm
Head diameter27 mm
Materialaluminium alloy body with HAIII hard-anodized finish

An extremely lightweight handheld flashlight weighs 60 g. A smaller flashlight is easier to carry in a pocket, bag, or pouch. This makes it more convenient for everyday use or when you're on the go. Aluminium is a lightweight material, which is beneficial for S43 LH351D flashlight. The body of S43 LH351D flashlight treated with a Type III hard-anodized, anti-abrasive finish. This flashlight comes in a sleek black color option.

Astrolux S43 LH351D / 6

System, LED, lens, reflector

Emitter4 x Samsung LH351D LEDs
Color temperature5000 K
Switchelectronic side

The emitter of S43 LH351D manufactured by Samsung, a Korean LED manufacturer. Color temperature is a characteristic of light. It is used to quantify the color appearance of light sources. The S43 LH351D's TIR lens is made of a single piece of transparent material. This material is typically acrylic or polycarbonate. The flashlight has electronic switches. They have many benefits and extra features compared to mechanical switches.

Astrolux S43 LH351D / 7

Performance, flux, intensity, throw

Flux4000 lm
Intensity8464 cd
Throw184 m
CD/LM factor2.12

The S43 LH351D flashlight has 4000 lm. It will provide an exceptionally bright and powerful beam of light. The S43 LH351D flashlight has 8464 cd. It provides a much brighter and more intense beam. The throw distance is the farthest distance the flashlight can light an object. The cd/lm factor is the candela-to-lumen ratio. It shows how concentrated a light source's output is. A flashlight with a higher CRI can show colors more accurately. This is useful for examining objects, it helps tell colors apart in low-light or nighttime. The flashlight has a CRI of 95. It can show colors with exceptional accuracy, and it also captures subtle details.

Astrolux S43 LH351D / 4

Software, user interface, modes

Mode memoryyes
Ramping modeyes

NarsilM is an open-source firmware designed for flashlights, it is similar to Anduril. The flashlight has mode memory. It remembers the mode you were using when the light was last turned off. It stays in that mode when you turn it on again. The S43 LH351D flashlight has ramping mode. Its user interface lets you control the brightness by pressing and holding a button. The S43 LH351D is tactical strobe ready. The strobe light is disorienting to the person it is aimed at, this makes it hard for them to concentrate. The SOS flashes Morse code so you can signal for help when needed.

Astrolux S43 LH351D / 2

Features, battery, protections

Battery1 x 18650 Li-Ion battery
Battery indicatoryes
Charger portmicroUSB
Thermal regulationyes

The Astrolux S43 LH351D flashlight is powered by 1 x 18650 Li-Ion battery. The battery indicator lets you know when the battery is low, charging, or fully charged. This flashlight can charge the battery with a built-in charger. It works with a USB power source. LVP (Low Voltage Protection) is designed to protect the battery. It stops over-discharging, which can reduce battery life or cause permanent damage.

The built-in thermal control adjusts brightness output to prevent overheating. The IPx6 rating indicates that the flashlight has a protection against water jets.

Astrolux S43 LH351D / 3

Accessories, package contents

Package contents18350 tube
spare o-ring
survival hammer

With a clip, you can fasten the flashlight to a reachable spot. This ensures it is easy to get whenever you need it. The lanyard prevents accidental loss of the flashlight. Replacing worn or damaged O-rings helps a lot. It keeps up the flashlight's durability and performance.

According to the ANSI/NEMA FL1 Standard, we measure the performance of the S43 LH351D flashlight 30 seconds after switching on the light. The ANSI/NEMA FL1 2009 Standard is a set of flashlight performance guidelines.

Conclusion, pros and cons

This Astrolux flashlight, like any other, has its strengths and weaknesses. Let's take a close look at both sides to understand this flashlight better. I share my thoughts on its standout features and the parts that might need improvement. Keep in mind, these are just my opinions, and you might have a different perspective.


  • lightweight
  • aluminium body
  • warm light
  • TIR lens
  • side switch
  • strong flux
  • superior CRI
  • NarsilM firmware
  • mode memory
  • ramping mode
  • tactical strobe
  • SOS/beacon function
  • battery indicator
  • USB charger
  • low-voltage protection
  • thermal regulation
  • waterproof
  • clip


  • no auxiliary LEDs
  • non-magnetic


Astrolux S43 LH351D / S43LH351D photo 1.
Astrolux S43 LH351D / S43LH351D photo 2.
Astrolux S43 LH351D / S43LH351D photo 3.
Astrolux S43 LH351D / S43LH351D photo 4.
Astrolux S43 LH351D / S43LH351D photo 5.
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Astrolux S43 LH351D / S43LH351D photo 7.
Astrolux S43 LH351D / S43LH351D photo 8.
Astrolux S43 LH351D / S43LH351D

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David Hagon
I love bushcraft and flashlights. I find joy in mastering wilderness survival skills and exploring the realm of illuminating gadgets. Bushcraft isn't just fun, it's a learning journey. I form a strong bond with nature. It's more than a hobby, it enriches me in practical and spiritual ways.
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