Operating Instructions

On/off

Tap the tactical switch to turn on the light silently, release it and the light will go out. 

Fully press the tactical switch to constantly turn on/off the light.

Switches 

The round tail switch is the tactical switch for instant burst.

The oval tail switch is the functional switch for output selection and instant strobe.

Output Selection 

With the light turned on, single click the functional switch to cycle through Low→Med→High→Burst.

Instant Burst

Fully press the tactical switch for 0.5 seconds to enter Burst and maintain this output.

Strobe Mode

With the light turned off, tap the functional switch to enter Strobe, release it and the light will go out.

With the light turned on, press and hold the functional switch for 0.5 seconds to enter Strobe, tap either switch again to exit Strobe and recall the previously used output, or fully press the tactical switch to turn the light off.

Intelligent Memory Circuit 

The light automatically memorizes the last selected output excluding Strobe. 

When turned on again the previously used output will be recalled.

Battery Specifications

*Do not use an 18650, CR123A, or 16340 battery.

*21700 Li-ion batteries are powerful cells designed for commercial applications and must be treated with caution and handled with care. Using low-quality batteries or mishandling batteries (such as short-circuiting or overheating) could lead to combustion and jeopardize the safety of users and property. Any adverse effects resulting from the use of low-quality batteries are not covered by any Fenix warranty or liability. Using quality batteries with circuit protection will reduce the potential for combustion or explosion.

Battery Replacement

Unscrew the light tail and insert the battery with the anode side (+) towards the light head, then screw the light tail back on.

Charging

1. Unscrew the light neck counterclockwise to reveal the charging port, then connect the USB Type-C end of the charging cable to the light. 

2. The indicator will display red while charging and will turn green when fully charged. 

3. Once charging is completed, be sure to unplug the charging cable and screw the light neck back to maintain the dustproof and waterproof ability.

Note: 

1. When charging fails or the battery is reversely connected, the battery level indicator will flash red or remain off to remind users to check the battery.

2. The normal charging time of the included Fenix ARB-L21-6000 battery is approximately 1.5 hours from depleted to fully charged.

3. Recharge a stored light every four months to maintain the optimum performance of the battery.

4. The light cannot be operated while charging.

5. Check the battery if the battery level indicator blinks or remains off. It is strictly prohibited to charge the light while using an 18650, CR123A, or 16340 battery.

*Note: The battery level indicator only works with a Fenix ARB-L21 Series rechargeable battery.

Battery Level Indication 

Each time the light is turned on, except for Strobe, the indicator (unscrew the light neck to see) will indicate the battery level and will last for 3 seconds. 

Green light on: saturated 100% - 85%

Green light flashes: sufficient 85% - 50%

Red light on: poor 50% - 25%

Red light flashes: critical 25% - 1%

*Note: This only works with a Fenix ARB-L21 Series rechargeable battery.

Intelligent Overheat Protection            

The light will accumulate a lot of heat when used at high output levels for extended periods. When the light reaches a temperature of 55°C/131°F or above, it will automatically step down a few lumens to reduce the temperature. When the temperature drops below 55°C/131°F, the light will gradually recall the preset output level.

Low-voltage Warning

When the voltage level drops below the preset level, the flashlight is programmed to downshift to a lower brightness level until Low output is reached. When this happens in Low output, the flashlight blinks 3 times every 5 minutes to remind users to timely recharge or replace the battery. 

*Note: This only works with a Fenix ARB-L21 Series rechargeable battery.

Usage and Maintenance

• Disassembling the sealed head can cause damage to the light and will void the warranty.

• Fenix recommends using an excellent quality battery.

• If the light will not be used for an extended period, remove the battery, or the light could be damaged by electrolyte leakage.

• Unscrew the light tail half a turn or take out the battery to prevent accidental activation during storage or transportation. 

• Long-term use can result in O-ring wear. To maintain a proper water seal, replace the ring with an approved spare.

• Periodic cleaning of the light and battery contacts improves the light's performance as dirty contacts may cause the lamp to flicker, shine intermittently or even fail to illuminate for the following reasons:
  A: Poor battery level.
  Solution: Recharge or replace the battery.
  B: The contact or contact point of the battery or light is dirty.  
  Solution: Clean the contact points with a cotton swab soaked in rubbing alcohol.

If the above methods don't work, please contact the distributor.

Warning

• Do NOT place this light in the reach of children!

• Do NOT shine the light directly into the eyes of anyone!

• Do NOT place light head near flammable objects, high temperatures can cause objects to overheat and become flammable/ignite!

• Do NOT use the light in inappropriate ways such as holding the unit in your mouth, doing so could cause serious personal injury or death if the light or internal battery fails!

• This light will accumulate a significant amount of heat while operating, resulting in a high temperature of the light shell. Pay close attention to avoid burns.

• Remove the battery to prevent accidental activation when the light is placed in a closed and flammable environment such as pockets and backpacks!

• The LED of this light is not replaceable; so the whole light should be replaced when the LED reaches the end of its lifespan.

What kind of LED is used in TK21R? Does Fenix offer to replace LED? 

A: One Luminus SFT90 cold white LED with a lifespan of 50,000 hours.

Fenix does not provide LED replacement services for the time being, and users are not recommended to replace the LEDs independently, which may affect product performance and cause product damage.

What is the working voltage of TK21R?

A: The operating voltage is 3.0V～4.2V；The maximum operating voltage range is 3.0V～5.5V.

What kind of battery can be used in TK21R?

A: It is recommended to use a Fenix 21700 Li-ion battery. Other Li-ion batteries are not recommended. As an unmatched battery may cause the flashlight to fail to work normally.

How to prevent accidentally activate the TK21R?

A: Unscrew the light tail, or remove the battery to prevent accidental activation.

What are the optional accessories for TK21R?

A:

AOT-04 Traffic wand、ALG-00 Rail mount、ALG-15 Rail mount、ALG-16 Rail mount、ALG-18 Flashlight ring、AER-05 Remote pressure switch、ALP-10L Flashlight holster、ALP-20 Quick-pull holster、ALR-01 Tactical flashlight ring、ALB-10 Bicycle light holder with GoPro interface、ALD-05 Flashlight helmet holder

Why does the TK21R downshift to a lower mode after being used for a while and the higher mode cannot be selected?

A: There are two reasons:

1. Intelligent Overheat Protection

   The flashlight will accumulate a lot of heat when used at high output levels for extended periods. When the light reaches a temperature of 55°C or above, the light will automatically step down a few lumens to reduce the temperature.

2. Low-voltage Warning

   When the voltage level drops below the preset level, the flashlight is programmed to downshift to a lower brightness level until the Low mode is reached.

What is the APF？

A: 

• The APF (Advanced Pulse-Frequency Transmission System) was developed by Fenix laboratory, a major technology breakthrough of flashlight industry. Allowing the tactical flashlight achieve a higher level of performance.
• Traditional forward switches are limited by current, and it is difficult to achieve brightness above 2000 lumens. In the age of 21700 batteries gradually expanding, 3000 lumens tactical flashlights are almost impossible; while the flashlight using APF technology can.
• Make the functional tail cap simpler. Traditional multi-function tail cap needs to achieve functional through the double-layer body or additional channels; and the flashlight using APF technology offering a strong reliable flashlight in simple structure, we talking about single layer body if specifically.
• Better anti-interference performance. Complex external environments such as strong magnetic fields are easily dealt through stronger anti-interference ability.

Why does the TK21R happen to flicker?

A: The reasons that may cause the light to flicker, shine intermittently or even fail to illuminate:

1. Poor battery level.
   Solution: Recharge or replace the battery.
2. The contact or contact point of the battery or flashlight is dirty.
   Solution: Clean the contact points with a cotton swab soaked in rubbing alcohol.

If the above methods don't work, please contact your authorized distributor.