Update 09/24/2024��������������������I purchased the big 5k lumens model as well. Although unfortunately it has a yellow filament as well as the new 2k lumens models, it is certainly brighter, but it is much larger. I don��t know how practical it will be in technical diving, will seeUpdate 09/01/2024-------------------------I assumed that the unit, I received was a lone wolf defective one, so I requested a replacement, which Unfortunately had the same exact issue with the yellow instead of white light, So I contacted the seller/ manufacturer, and with it's up and downs, overall all it was a very pleasant experience, as they were responsive in a timely manner and they stood behind their product and cared about customer support and satisfaction, regardless if the change they made is for the better as they claimed or not.* First, they actually admitted my finding and the mid cycle life change that the model went through, getting a different light filament, instead of denying (which obviously will be hard as I have proof of it)* Second, they were keen enough, to explain to me, why they decided t make the change. The claim was that the yellow light will actually penetrate better/ deeper under water. Wether this is true or not, it os something to be seen in real life, because it doesn't make sense to me, for couple of reasons1- The wavelength color absorption/ penetration charts/ laws etc, only applies to light coming from the SURFACE/ SUN light when being seen from under water, as not all the wavelengths will make it through, depending on the absorption of the different wavelengths at different depths etc and that applies also to colored objects being seen under water with NATURAL sun light .....and the best evidence to that , and Tech divers, will know what I am talking about, is that when you go to around 60-70 meters under water, then all of a sudden everything is monochromatically blue, because at that depth only the blue wavelength can penetrate that depth, but when you introduce a whole spectrum light at the same depth from a strong light source, all of as sudden the natural red, violet, green color of the corals, fishes etc get fully restored, because you compensated for all the missing wavelengths that got absorbed in the way, and there is no penetration/ absorption factor (at least not as significant one, compared to light from the surface),so now the objects absorbs all the wavelength of the new light spectrum and only reflects their own, and hence we see their true color2- IF and Only if penetration/ absorption will still play an important factor, then Blue penetrate deeper than yellow, and of course since we can't use blue only, then the next best thing will be bright white (daylight) and not yellow light, which will be closer to the blue spectrum and will still theoretically penetrate deeper, if one believes that this is still a major factor, which I don't believe so* Third, they offered to send me an old head light only with the white filament from the factory in china, without the accessories, in exchange for updating my review, which I agreed on the condition that I will only update the original review, and I won't take it down, just to be honest and to make people aware of the potential issue and make their own decision. I know not everyone is going to notice/ care and be picky like me and in all honesty, if I didn't have the old unit with the white light, I would have not complained or noticed the difference, because overall it is an excellent product, like most of their other products that I have bought multiple times now over the last few 3 years or so, I just wish for they particular one, they come up with a better lock mechanism for the light switch, since, although it works great above water, no matter how hard I try, I always found it turned on in my pocket, either by the time I made it to the bottom or when I am back on the surface ...Anyways, after exchanging few e-mails back and forth with very responsive customer, in a timely fashion they decided to send me a whole unit, with the old white light filament, including the accessories unconditionally and told me to keep the original one I ordered from Amazon as well.I originally was planning to wait till I receive the old unit and actually try Bothe white and the yellow light under water, but I decided not to do, that, since I am afraid I may forget, get busy and don't have a chance to do it, so I decided to update the review with the overall top notch customer service experience, even before I physically receive the unit, which they shipped and send me the tracking number.I will try to make a second update in hopefully a couple of month from now, when I get a chance to test the old white, versus the new yellow light side by side under deep water and see if their theory/ reasoning for change will actually hold true or not, even though it theoretically didn't make sense to me, but I can be wrong ... but overall I don't think the differ...