Fenix TK35R Reference Manual and SpecificationsUpdated 2 hours ago

This is the Fenix Store reference guide for the Fenix TK35R rechargeable tactical flashlight — condensed from the manufacturer's official manuals for easier reading. The TK35R is available in two light-source variants, UV Light and Red Light, sharing the same body and white-light performance. Downloadable PDF versions for each variant are also available on the product page.

Overview

• 5800 lumens maximum white-light output and 610 meters maximum beam distance
• Utilizes four Luminus SFT25R LEDs, plus either one Luminus SST08 UV LED (365 nm) or one Cree XEG red LED, depending on variant
• Powered by two included Fenix ARB-L18-4000 batteries
• Flexisensa toggle switch for seamless switching among General/White mode, Lockout mode, and the secondary light mode (UV or Red)
• Silent dual tactical switches at the light tail for instant burst/turbo and instant strobe
• USB Type-C charging port with sliding port cover
• Battery level indication and low-voltage warning
• Intelligent overheat protection
• Made of high-intensity aluminum alloy
• Size: 6.06'' x 1.69'' / 154 x 43mm
• Weight: 12.06 oz / 342 g (including batteries)

Technical Parameters (ANSI/PLATO FL1) — White Light

Impact Resistance: 1 meter  |  Waterproof Rating: IP68

*Turbo/Burst runtime includes reduced-output time from thermal/protection step-down. Specs measured by Fenix using two ARB-L18-4000 batteries at 21±3°C / 50–80% humidity; real-world performance varies.

UV Light Variant

A high-precision 365 nm UV LED, useful for authenticating documents, credentials, and security codes. Since UV light is largely invisible to the eye, the battery indicator alternately flashes red and green as a reminder whenever the UV light is left on, to prevent accidentally draining the battery.

Red Light Variant

Red light preserves night vision and is commonly used for tactical, hunting, and low-light signaling use. The battery indicator alternately flashes red and green as a reminder whenever the Red light is left on.

Operating Instructions

Mode Switching: rotate the toggle switch to the left end for White/General mode, to the right end for the secondary mode (UV or Red, depending on variant), and to the middle for Lockout/off mode.

On/Off: with the light off and unlocked, tap the tactical switch to turn the light on silently (release to go out), or fully press the tactical switch to turn it on constantly (press again to turn off).

Instant Turbo/Burst: with the light off and unlocked, fully press the tactical switch for 0.5 seconds to enter maximum output and stay there; single-click the functional switch to shift to Eco, or fully press the tactical switch to turn off.

Strobe: with the light on, press and hold the functional switch for 0.5 seconds to enter Strobe (White mode) or the flash mode of the active secondary light. Single-click the functional switch or tap the tactical switch to recall the previous output.

Output Selection: in White/General mode, single-click the functional switch to cycle Eco → Low → Med → High → Turbo/Burst. In the secondary mode, single-click to toggle between the High and Low levels of that light source.

Intelligent Memory Circuit: the light remembers the last-used output level (excluding Strobe/flash modes) and recalls it the next time it's turned on.

Battery & Charging

Uses two Fenix ARB-L18-4000 (or ARB-L18 series) 18650 batteries, 3.6V, included. To replace: unscrew the light body and insert the batteries anode side (+) toward the light head, then screw the body back on. Do not use 16340 or 21700 batteries, and don't mix battery brands, sizes, or types.

To charge: slide open the port cover on the light tail and connect the included USB Type-C cable. The indicator glows red while charging and turns green when full. Charging takes about 2 hours with a 9V/3A adapter, or about 4 hours with a 5V/2.4A adapter. Recharge a stored light every four months to maintain optimum battery performance.

Battery Level Indication

Each time the light is turned on, the indicator briefly shows battery status (lasts 3 seconds); works with Fenix ARB-L18 series batteries.

• Green, on: 100–85%
• Green, flashing: 85–50%
• Red, on: 50–25%
• Red, flashing (fast): 25–1% (recharge soon)

Protection Features

Intelligent Overheat Protection: at 60°C/140°F or above, the light automatically steps down a few lumens to cool down, then gradually restores the preset output once temperature drops.

Low-Voltage Warning: as the battery depletes, output automatically downshifts; at the lowest output the indicator blinks red slowly as a reminder to recharge or replace the battery. The light stays on until the battery runs out or protection triggers, rather than shutting off automatically.

Care & Maintenance

• Do not disassemble the sealed head — this voids the warranty.
• Use only high-quality, protected batteries; low-quality or mishandled batteries are a fire/safety risk and are not covered by Fenix warranty.
• Remove the batteries for storage if the light won't be used for an extended period, to avoid electrolyte leakage.
• Lock the light or remove the batteries during storage/transport to prevent accidental activation.
• Replace the O-ring with an approved spare if it shows wear, to maintain the waterproof seal.
• If the light flickers or won't turn on, clean the battery contacts with a rubbing-alcohol-soaked cotton swab.

What's Included

Fenix TK35R flashlight (UV or Red light variant), 2 x ARB-L18-4000 batteries, USB Type-C charging cable, holster, lanyard, spare O-ring, product leaflet, and warranty card.

Have a question this guide doesn't answer? Contact Fenix Store support and we're happy to help.