Klarus XT11 Upgrade 820 lumens

Review: Klarus XT11 Upgrade Version


The Klarus XT11 is a compact tactically oriented flashlight notable for its cleverly designed two-button tailcap which is used for activation and mode switching.  Designed for hunting, military, or self-defense use, the XT11 produces three output levels as well as a flashing strobe mode and can be powered by a single 18650 lithium-ion rechargeable battery or two 123A lithium primary cells.

Two variants of the XT11 are available, both using the Cree XM-L2 LED.  The original XT11 is rated to produce 600 lumens in its highest mode and features a stainless steel strike bezel.  The XT11 Upgrade version has a higher maximum output of 820 lumens and has a slightly more aggressive crenelated bezel ring.

This review is based upon the XT11 Upgrade version which typically retails for around $80.

Klarus XT11 Upgrade Version – Overview

The Klarus XT11 arrives in a cardboard and plastic retail package which allows a full view of the light inside.

Klarus XT11 Upgrade version 820 lumens

In addition to the XT11, the package contains a spare switch boot, lanyard, removable pocket clip, removable tactical ring, holster, and spare O-rings.  An optional filter kit is also available which includes a white diffuser along with red, green, and blue filters.

Klarus XT11 Upgrade 820 lumens

The light itself is constructed of aircraft aluminum with a dark gray hard-anodized finish that is well matched across all parts of the flashlight.

Klarus XT11 Upgrade 820 lumen

The light is easily disassembled into its component parts – Head, body, tailcap and tactical ring.  All parts thread together very smoothly.  The pocket clip can also be removed without the use of tools.  O-rings installed at the head and tail help the XT11 achieve an IPX-8 rating against water ingress.

Klarus XT11 Upgrade 820 lumens

The head of the XT11 features a finned base and is topped off with the removable crenelated bezel ring.

Klarus XT11 Upgrade 820 lumens

The bezel ring is easily removed by hand allowing the installation of the optional filters or diffuser (not shown).

Klarus XT11 Upgrade 820 lumens

Battery contact at the head is maintained, even under recoil, through the use of a brass spring.

Klarus XT11 Upgraded 820 lumens

The body is finished with a checkered pattern for improved grip.  The removable pocket clip snaps securely into place and is held in place by friction against the body.

Klarus XT11 Upgrade 820 lumen

Lettering is a slightly off-white color and is very sharp and legible against the dark gray background.

Klarus XT11 Upgrade 820 lumen

The removable tactical ring installs between the tailcap and body.  The ring also provides an additional lanyard attachment point and is able to rotate freely around the body of the flashlight.

Klarus XT11 Upgrade 820 lumens

Inside the tailcap a brass spring-loaded button is used to make and maintain battery contact.  Batteries may be loaded from either the head or tail.

Klarus XT11 Upgrade 820 lumens

The tailcap houses the two switches and has raised edges which provide a lanyard attachment point and protect against accidental activation.  The main switch protrudes slightly beyond the raised edges meaning the XT11 cannot tail stand.  A flat area is machined into the outer edge of the tailcap to allow indexing the light so that the user’s thumb is properly aligned with the switches.

Klarus XT11 Upgrade 820 lumens

User Interface

The two tailcap switches have distinct purposes with the taller round switch serving to turn the XT11 on and off and the shorter mode button used to cycle through the operating modes.

Klarus XT11 Upgraded 820 lumens

The main switch is a forward clicky and allows momentary operation with a partial press and constant-on operation with a full press and click.  The XT11 always turns on in high mode first.

When the light is on, each press and release of the mode button will advance to the next output mode (High -> Medium -> Low -> Back to High).  Holding the Mode button for 2 seconds will activate the strobe mode.

The strobe mode may also be accessed directly while the XT11 is off by pressing the Mode button.

Klarus XT11 – Manufacturer’s Specifications

Klarus XT11

Klarus XT11 Upgrade

Output (High Mode)

600 Lumens / 2.2 hours*

820 lumens / 3 hours**

Output (Medium Mode)

150 lumens / 7.3 hours*

160 lumens / 10 hours**

Output (Low Mode)

10 Lumens / 295 hours*

11 Lumens / 73 hours**

Output (Strobe Mode)

600 Lumens / 4.4 hours*

820 lumens / 6 hours**


5.8 inches (144 mm)

5.9 inches (149 mm)

Body Diameter

1.0 inch (25.4 mm)

1.0 inch (25.4 mm)

Bezel Diameter

1.375 inches (34.9 mm)

1.375 inches (34.9 mm)

Weight (Without Battery)

4.7 ounces (132 grams)

4.7 ounces (132 grams)

* With 2200mAh 18650 battery          ** With 3100mAh 18650 battery

Klarus XT11 Upgrade Version – Performance

The XT11 uses a Cree XM-L2 emitter housed behind an ultra-clear glass lens to produce up to 820 lumens.  The LED’s output is focused by a textured orange peel reflector resulting in a fairly floody beam with a pronounced center hot spot.

Klarus XT11 Upgrade 820 lumens

Overall, the XT11’s beam has a cool tint, most noticeably in the spill portion.  The center spot is nearly white with the surrounding corona showing some hints of green tint.

The following slides show the Klarus XT11 Upgrade compared to a variety of other lights to give some perspective with regard to output and beam profile.  The images can be compared across their full width using the slider and additional comparisons can be viewed by using the navigation buttons in the bottom-right corner of each image.

The following lights were used in the comparison:

  1. SureFire P2X Fury (Link to review)
  2. SureFire EB2 Backup (Link to review)
  3. Elzetta Bravo with AVS Head (Link to review)
  4. Streamlight ProTac HL
  5. SureFire M3LT
  6. Elzetta Charlie with AVS Head (Link to review)
  7. Malkoff MD4 with M91A
  8. SureFire P3X Fury (Link to review)
  9. Malkoff Hound Dog XML2

Klarus XT11 Upgrade Beamshots (30 Yards to Swing)


Klarus XT11 Upgrade – Runtime

Runtime tests were conducted with Battery Station 123A lithium primary cells and an AW 3100mAh 18650 lithium-ion rechargeable battery.

Klarus XT11 Upgrade 820 lumens

With both battery types, the XT11 Upgrade ran for four minutes at full output before stepping down to just over 50% of its initial output and beginning a long decline as the batteries were depleted.

Klarus XT11 Upgrade 820 lumen runtime

The Battery Station 123A cells gave the highest output during the initial portion of the test and provided just over 75 minutes of runtime before the XT11 shut off.  The AW 18650 ran for much longer, providing over 3.5 hours of total runtime before the light shut itself off.  During the runtime tests, the head became slightly warm during the initial part of the test but never got hot due to the step-down in output.

Although the XT11 operating voltage is listed as 3.5V-8.4V, no test was performed with 2×16340 cells.  The XT11 operator’s manual specifically states this type of battery should not be used.

Klarus XT11 Upgrade – Conclusions

The XT11 is a really nice looking light that has many of the popular “tactical” features such as a crenelated bezel, tactical grip ring, and instant access to high and strobe output modes.  The anodized finish is applied very evenly and all machining appears to be very nicely done.  The various parts thread together smoothly with very little play in the threads.  For a light that is intended to be used with rechargeable cells, the tailcap button (rather than a spring) is a nice touch as it should reduce wear on the negative battery terminal.  It does seem odd that the XT11 is rated to operate up to 8.4 volts but the use of 16340 lithium-ion cells is not allowed by the operating manual.

The two-button tailcap provides a nice way of instantly accessing high and strobe modes as well as cycling through the lower levels.  Operation is intuitive and easy although activating the light with the pad of my thumb often resulted in me pressing both buttons at almost the same time, turning the light on and then immediately shifting it into the medium output mode.  Using the tip of my thumb helped prevent this but the position feels unnatural compared to how I have used other lights.  The switches worked well during the review although I do wish the mode button were a little bit lower or required more travel before activating.

Output is very respectable even though the XT11 does not initally appear as powerful as some other 600-900 lumen tactical lights.  Some of this perceived difference is likely due to the floody beam generated by the large XM-L2 emitter coupled with the relatively small head and orange peel reflector.  The step-down in output during continuous operation has become the norm but the fact that the XT11 does not run in regulation after the step-down is somewhat surprising.  Also, the fact that the light simply shuts off when the battery voltage gets to a certain point is a little disappointing, particularly with the 123A primary batteries.  Although this shouldn’t matter 99% of the time, it could result in the user being literally left in the dark when the light unexpectedly shuts off.

Although I’m not a fan of snap-on pocket clips, the one provided with the XT11 seems to hold very tightly and stays in place well.  I used the clip to my advantage by positioning it in line with the tailcap buttons so that when holding the light in an overhand grip with the clip at the 12 o’clock position, the tailcap buttons are properly oriented for my thumb to use them.

My biggest knock against the XT11 is the very audible whine heard while the light is in operation.  It is easily the loudest whine I have heard from a light and I can literally hear it from across a room if there is no background noise.  The whine is present at each output level, changing only in pitch at lower levels, but I was not able to hear it when the XT11 was in strobe mode.  Although it’s possible the noise means nothing, it still raises a flag, especially with a light that is supposed to be weapon mountable.

When it’s all said and done, the Klarus XT11’s biggest selling points are going to be its price and feature set.  I do believe it’s a little more “tacticool” than “tactical” and it is better suited for general use rather than in a hardcore tactical environment.


  • Two-button switching allows instant access to high or strobe modes
  • Compatible with primary and rechargeable batteries
  • Machining, fit and finish are very nice
  • Pricing


  • Whine raises questions about the quality of the electronics
  • Sudden shut-off means a user could go from having around 200 lumens to nothing as the batteries are depleted
  • Too easy to accidentally switch to medium mode when turning the light on

The Klarus XT11 is made in China.  Additional information about the Klarus XT11 Upgrade can be found on the Klarus website.

The lithium primary 123A batteries used for runtime testing were provided by the good people at Battery Station.

Posted in Flashlight Reviews, Other Products and tagged .

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