Operation Instruction
Dual Tactical Tail Switch
The main tactical switch is larger, the secondary mode switch is smaller.
ON/OFF
Tap and hold the tactical switch to turn on the light temporarily, release it the light will go out. Fully press the tactical switch for constant-on illumination, press again to turn off the light.
Output selection
When the light is on, click the mode switch to cycle through Turbo→Low→Mid→High.
Strobe mode
When the light is on, press and hold the mode switch for 1 second to enter into Strobe mode, press again to return to general mode.
When the light is off, press and hold the mode switch to activate strobe mode temporarily.
Intelligent Memory Circuit
The Fenix TK16 memorizes the last brightness level used in the general mode, but it will not remember the Strobe mode. The next time you turn on the flashlight, it will activate the last brightness level you selected.
Over-heat Protection
The light will accumulate a lot of heat when it is working at Turbo brightness level. When it works at Turbo for 20 minutes or above, the flashlight will automatically adjust the output to prevent the light from overheating.
Battery Specification
| Type | Dimensions | Nominal Voltage | Usability | |
| Fenix ARB-L2 Series | 18650 | 3.7V | Recommended | √ |
| Non-rechargeable Battery(Lithium) | CR123A | 3V | Usable | √ |
| Rechargeable Battery(Li-ion) | 16340** | 3.6V/3.7V | Cautious* | ！ |
| Rechargeable Battery(Li-ion) | 18650 | 3.6V/3.7V | Cautious* | ！ |
| Rechargeable Battery(LiFePO4) | 16340** | 3.2V | Usable | √ |
| Rechargeable Battery(LiFePO4) | 18650 | 3.2V | Banned | × |
Warning: Please do not mix batteries of different brands, sizes, capacities or types. Doing so can cause damage to the flashlight or the batteries being used.
*18650/16340 Li-ion batteries are powerful cells designed for commercial applications and must be treated with caution and handled with care. Quality batteries with circuit protection will reduce the potential for combustion or explosion but cell damage or short circuiting are potential risks the user assumes.
**Only compatible with convex anode battery.
Battery Replacement
Unscrew the tail cap to insert the batteries with the anode side (+) toward the light's head, screw the tail cap back on.
Usage and Maintenance
- Disassembling the sealed head can cause damage to the light and will void the warranty.
- Fenix recommends using excellent quality batteries. If the flashlight will not be used for an extended period, remove the battery, or the flashlight could be damaged by electrolyte leakage or battery explosion.
- Unscrew the tail cap one-half turn or take out the battery to prevent accidental activation during storage or transport.
- Low-voltage Warning Function: When the voltage level drops below the preset level, the flashlight is programmed to downshift to a lower brightness level. When this happens in Low output mode, the flashlight blinks three times every five minutes to remind you to replace the battery. To ensure normal use, the flashlight will not turn off automatically and will work until the batteries run out completely.
- 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 battery contacts improves the flashlight's performance as dirty contacts may cause the flashlight to flicker, shine intermittently or even fail to illuminate for the following reasons:
Reason A: The batteries need replacing.
Solution: Replace batteries (Please confirm the correct installation of anode and cathode). Reason B: The threads, PCB board contact or other contacts are dirty.
Solution: Clean the contact points with a cotton swab soaked in rubbing alcohol. If the above methods don't work, please refer to the warranty policy before contacting your authorized distributor.
*Notice: The routine cleaning video can be watched and downloaded through Fenix official website, please log onto the service channel->“maintenance for light”.
