once again could someone who knows how please describe the steps for setting this light back to DEFAULT. (thanks).
teacher does a great job of explaining it in the link below. Check the second heading of his post titled “Thermal Configuration & Protection”
Wrong joke. 
With the factory reset function (which, unfortunately, wasn’t made until after D4V2 was produced):
- Let the light settle to room temperature, ~21 C or so.
- Loosen tailcap. Hold button, tighten tailcap, continue holding button for ~4 seconds.
- Let go after the bright flash.
Without the factory reset function (which is how the first batch of D4V2 works):
- Exit muggle mode, if you’re in it. Or exit momentary mode. Or exit lockout mode. Or whatever. Get back to regular “off” mode.
- For each setting, navigate to that setting and change the value. Settings include:
- Smooth ramp floor / ceiling.
- Stepped ramp floor / ceiling / number of steps.
- Smooth/stepped ramp toggle.
- Turn off manual memory.
- “Off” mode aux LED color and pattern.
- “Lockout” mode aux LED color and pattern.
- Beacon mode speed.
- Which strobe-group mode is active?
- Speed / brightness for each strobe-group mode.
- Temperature sensor calibration.
- Temperature limit.
- Repeat for each setting in the list. May require looking up defaults in the source code (usually just the light-specific config file).
So… a complete reset to defaults is generally not recommended. There are several things to configure, and the details are different for each. Most people probably want to just identify which particular setting they want to change, and then change it.
Does anyone know a source of single 10621 optics in the UK (or EU)? Ive been wanting to try one out for a while but no one seems to be selling them in anything but large order quantities. MTN shipping is too expensive
Mine arrives today!
sand, xpl 3a
Oh my, that’s a lot of muscle and flesh to take in. Especially on my monitor at work…
You’re right though, why would TK be interested in anybody who clearly doesn’t have the pockets to carry at least two flashlights at once? This isn’t an r/buttlight scenario is it?
Probably best you don’t look that subreddit up…
Conrad
I’ve had luck with Arrow before.
Arrow got rid of their free shipping for orders under $50 
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nice! Maybe someone will appreciate this light and do a write up on it. Can’t believe the lack of fanfare on this light. Or maybe it’s a dud and not deserving of any fanfare at all. I’m perplexed honestly. Emisar has always been rather exceptional. Several are in possession of the light and very little spoken about it. Yadayadayada.
TK’s review is so thorough and most people who went with Free shipping dont have their light. Give it a week or so
well, TK said the same thing, WAIT until they have the light. But in other offerings MUCH has always been said in anticipation of a great new offering. I am excited about this light. Mine has arrived close by, should have it any day now. Sure , I have a D4, but it’s the aux LEDs of the D4v2 that I’m giddy about …… oh, and momentary strobes
Who cares what’s said before people have it in their hands?
I ordered some parts to try and make a few flashing keys. There’s some anticipation for you
I agree that the excitement for the D4v2 isn’t as much, at this point, as it was, say, for the FW3A. Frankly, although I don’t have a FW3A, it’s difficult for me to understand all the hoopla over the FW3A when you compare the features of the two lights.
I think the D4v2 has so much more to offer, not the least of which are the multi color auxillaries, which can serve a useful purpose, such as monitoring the battery voltage. The capability of having a user selectable fixed initial on-level is not something you will find on the FW3A, let alone the auxillaries. Another thing that the FW3A doesn’t have is the 0
5/1.0 lumen momentary while in lockout. That feature combined with separately selectable auxillaries for lockout mode, makes lockout paradoxically usable. For example,at night, while in lockout, you can easily switch from bright red auxillaries to a momentary moon mode to light your way to the bathroom. In this way, you will never accidentally turn the light on in a bright mode that might disturb your partner. In addition to all of this, the D4v2 can be reduced in size with replacing the 18650 tube with the optional 18350 tube. Can the FW3A do this? No.
What then is the FW3A/FW3C hoopla all about. I think it boils down to two things. This light was largely designed by the BLF. It has an end switch, which for many is a plus. For some that may be even essential, who wouldn’t even consider a light like the D4v2 that has a side switch.
Again,I think the story on the D4v2 is only beginning. Not everyone who has gotten their D4v2, will give their feedback, as I have just done. Within the next 10 days, more people will be getting theirs, and we should hear a lot more.
I’m quite interested in the D4v2.
But the fact of the matter is my shipment just hasn’t arrived yet.
It’s a lot easier to get hyped up over my shiny new FW3As and FW3C when they are in my greedy little hands. 
I’ve made a few posts on Reddit about it. Wanted to do a video review but my equipment isn’t up to scratch to achieve a level of quality I will accept. I think most of us who have our D4V2s are too busy playing with them though, to be honest.
It’s a great light and the firmware feels so much better than on the fw3a.
I wonder if changes were made on the timing. It just feels more snappier and I don’t get any accidental turbo when I briefly turn the light on and of. I have that quite often on my FW3a
The second run FW3As have updated firmware. My FW3C has the two stage lockout, though it is lacking the option for manual mode memory. The D4V2 still wins on how up-to-date the firmware is.