flash indicates DEMO mode, 2 flashes indicate DAILY mode. (During this operation, the display will show the "DEMO" or "DAILY" mode to inform the user.) Unscrew the ring below the head to reveal the USB-C charging port. Everything is perfectly machined and there’s an o-ring to maintain its IP68 waterproof rating. The torch has a Luminus SST-40 LED behind a TIR lens and has a decent maximum throw of around 146 metres, or 5397 candela.

The slightly textured shell of the flashlight provides enough grip on the light to keep it from sliding out of your hand. The beam of the Nitecore T4K has a not too cold white tint and no particular artifact or dominant. The beam is alluvial in nature but in any case the "HIGH" level of 200 lumens allows a good view during the walk. Instead, leave you amazed by the large amount of light (4000 lumens), even if for a few seconds, of the Turbo level. Turbo on the T4K lasts for around 10 seconds and shows a progress bar in reverse, in effect the timer counting down. Realistically it’s not a bad thing – the light is very warm by the end of the timer, and running it for 20 seconds would probably have it be either unreasonably hot or severely throttled by thermals. I usually wouldn’t use a turbo mode for more than that long on something like this anyway, and I’ve been trained by the Emisar D4v2 not to use it for that long, so I don’t see that timer as an issue. Another information on the display is that of the 4000 lumens TURBO mode (lasting about 10 seconds). Let's see the sequence:Fenix are well known for their well regulated constant outputs and the E18R V2.0 is no exception – all the modes up to high were pretty much spot and with a constant output. I measured turbo at 1279 lumens at turn on, 1230 at 10 seconds, 1182 at 30 seconds, 563 at 5 minutes and 415 lumens at 10 minutes. The LEDs behind the TIR optic provide a very floody beam with almost no hotspot – together with the natural colour temperature it’s a great torch for walks. With a slightly lower maximum output than spec’d I measured 116 metres of throw and 3383 candela – Acebeam quote 153 metres of throw and 5875 candela. As expected, the light holds its output pretty solidly for close to the times advertised. On High I got 2:25h vs 2:45h advertised, but the room was hotter than usual (good old summer heat), but on Mid I got 7:27h vs the 7h advertised. And some longer batteries with protection circuits won’t fit, for example this Keeppower one. But I did find this Lumintop 14500 with built-in USB-C charging fits – I would have preferred Wurkkos included a battery like this with the torch – it would be far more convenient for newcomers to these higher performance torches. The torch weighs just 51.9g (1.83 oz). The Wurkkos TS10 comes in a plain box with a lanyard, spare o-rings and a user manual. This is an AA style torch but will only take 3.6V Li-ion 14500s – it needs at least 3V and won’t work with standard 1.5V AA Alkaline or NiMH batteries unfortunately.

The torch I always have on me whatever, is still the RovyVon Aurora A8 I looked at in the keychain torch roundup. Small sample of headtorches I’m testing, ready for next article … Under the OLED display there are the two electronic switches with which we will manage the NitecoreT4k. The two switches are protruding and provided with LEDs under the buttons. As can be seen from the symbols above these, one has an ON/OFF function (Power Switch) and with the other we will vary the 4 levels available beyond the momentary Turbo (Mode Switch). But for me it comes down to a toss up between the smaller still Fenix E18R V2 and Olight Baton 3 both with similar outputs, and I’d honestly grab either. I prefer the user interface on the Baton 3 and the charging case is great but I like the standard USB-C charging on the Fenix and the non-rechargeable CR123A battery support. The T4K features a user-friendly interface with a single side switch for convenient operation. It offers five brightness levels and three special modes, including strobe, SOS, and beacon, providing versatile lighting options for different situations.

DMM: UNI-T UT139C and UNI-T UT210E – 16AWG wire is used directly into the 139C via some banana plugs, and 8AWG wire in a loop for the UNI-T. The DMM I use depends on how high the expected current will be – I use the 139C for <10A, and the 210E for >10A. Note: *Turbo mode is a manually operated momentary function and therefore a run-time is not available. Nitecore did not disclose the tint (color temperature) and/or the CRI (Color Rendering Index) for the LED used in their light. For this light, a guesstimate would be in the 6500K and 70CRI ballpark. I also have the SC21 Pro from Sofirn which is very similar but almost half the size and weight, running off a 16340 battery. And it has the option of a higher CRI, warmer LED which I do slightly prefer. And the torch does come with a better than average IP68 dust and waterproof rating like the two Fenix torches in this roundup. The battery’s red turns green when the battery is fully charged.

For a rechargeable flashlight that is low weight, compact but able to put out a seriously bright light then the T4K is a great option. At just 76g and capable of an output of 4000 lumens this is an impressive piece of kit.

It appears the manual is based on the brighter 6000K version – but even with that version I doubt you’ll get the outputs in the manual, which is a little misleading. The manual states 1400 lumens of output based on the ANSI FL1 standard which is measured 30 seconds after switching the torch on. Nitecore's T4K Rechargeable Light 4000 Lumens is an impressive flashlight with a number of handy settings. The light output goes from 1 lumen up to 4000 lumens. Admittedly, the 4000 setting can only be used in very short bursts but it is so bright you're unlikely to need it much. The 200 lumen setting is certainly bright enough for most tasks around camp and for general use and the run times for each of the lower settings are impressively long. It would be nice if there was an actual TURBO mode within 500 to 1,00 lumens range, rather than a 4,000 lumens MOMENTARY TURBO mode. However, Nitecore probably went with a MOMENTARY TURBO instead, much like the Nitecore TM10K model. Tint & CRI I didn't notice PWM in the various brightness levels. The distance from the start of the spill to the feet is minimal.