Does the e21 version come with the frosted optic by default?
Yes. I believe it comes with the 10623.
That’s awesome. No coupon codes right? I figure I’d like to try e21 at 2700K.
No coupons. Hank’s prices are great all the time.
Hey what’s the advantage of the frosted optic, particularly l with warm lights? I’m just dipping my toe in the non-6500K water and anxiously awaiting my 2000K KR4 from Hank
The E21A emitter doesn’t look great in the default smooth optic… so it uses a frosted optic instead. I think it’s mostly just that the optic wasn’t designed for E21A, so the beam needs a bit of extra smoothing.
Normally it wouldn’t be an issue; most LEDs have kind of a similar visual effect in the throwiest optic. However, E21A is about the aesthetic qualities of the beam, so it makes sense to prioritize that instead of prioritizing the amount of throw.
Does anyone know if the brass used for the D4v2 is lead-free?
Lead is very common in brass, so if a specific alloy is not listed, I would assume there is some lead present.
I looked into this topic a little bit a few months ago, and found there are some studies of people who work with brass and bronze regulalry (machinists and locksmiths, both of whom generate small particles, which should be a worst case). Even for occupational exposure, the risk appeared to be pretty small.
Thanks for the reply! I think you are probably right about a very low risk. I have just always been OCD about things my whole life.
FYI, I found the main study again from my prior research. It is a smaller study population than I thought I remembered, but although not large enough to show statistical significance, I still find it encouraging. They say blood lead levels were about 50% higher on average in locksmiths than for their control subjects, but even these elevated levels were still low compared to the level where further actions are recommended (3.1 microgram/dL, vs 5.0 microgram/dL action level). Even that lowest action level calls only for future blood testing to make sure the concentration isn’t getting worse.
I’m far, far more worried about lead exposure from soldering and indoor gun ranges (where fumes or particles can actually be inhaled) than I am from handling brass or even bare lead like fishing sinkers.
You won’t breath lead when soldering. All the fumes are from the flux (and THAT is really nasty stuff).
Couple of questions from the uninitiated:
Batteries - I’ve got some 30Q’s that I’ll use if I stick with the full size tube, but I’m not sure on what 18350’s to go with if I go down that route.
And when ordering I added the AR coated glass without really knowing why - I just figured that at $2.50 it was worth buying and seeing if it was useful later. But I’ve no idea what it does or whether or not it’s worth replacing. Was it worth getting?
Keepower 18350 are good if you can source them.
The original lens is AR coated so you just ordered a spare lens 
One of my regular suppliers has the button top Keepower 1200mah IMR, will the button top be an issue with the D4V2?
Mine are flat. Not sure someone else might chime in?
I got my D4V2 a couple of weeks ago. Great light
Just a question on adjusting the temperature limit. How do I toggle between setting the temperature limit and setting the current temperature after entering thermal config mode?
Thanks
Current temperature is menu item #1. Temperature limit is menu item #2.
It’s recommended to not bother with that menu at all though. Just let the light settle to room temperature and do a factory reset. (loosen tail, hold button, tighten tail, hold button for ~4s until it does a bright flash) That should auto-calibrate the sensor and set the limit to a reasonably safe temperature.
The menu isn’t really necessary unless you want to raise the temperature limit.
“let the light settle to room temperature”
Thank you for this tip. Question: What if I do the factory reset while the light is hot? And conversely... ... ... What if I do the factory reset while the light is at frigid temperature? Which one of these two scenarios will raise the temperature limit?
The factory reset tells the light what temperature is “normal”. It then sets the limit somewhere above that, like a couple dozen degrees C higher. On most lights, it’s 24 C higher… because “room temperature” is assumed to be 21 C and the default limit for most lights is 45 C.
So if you want a higher limit without using a menu, warm it up a little before the factory reset.