Nitecore has already made quite good and really bright headlights: Nitecore TIP SE (700lum) and Nitecore TUP (1000lum). Any of these models have exceptional brightness for their size and are a good wow thing. The manufacturer did not stop there and brought the maximum brightness threshold to a whopping 4000 lumens.
Taking into account the fact that physics dictates all the same restrictions, the question of the actual duration of work in this mode remains open. Undoubtedly, such brightness will be accompanied by a colossal release of heat, which the flashlight will not be able to remove simply because of its size. As you can see, there is a dash in place of the duration of the work. Yes, and a 1000mah battery for such brightness suggests that it will only be achievable when fully charged. However, it is impossible to guess, past models proved to be unexpectedly good, not like turbo-puffed toys.
Otherwise, you should expect a size similar to the Nitecore TUP, adjusted for a larger head size. That is, a frank Nitecore T4K flashlight can be called a stretch. Rather, it is an ultra-compact flashlight. And super-bright, of course, for its dimensions (82x30x29mm).
Management seems to remain unchanged.
For those who are interested, since the release of the extremely popular Nitecore Tube, the manufacturer has made a lot of generally good models.
Official model page