The P20iX is a tacticool type 21700 size light. It's very floody - perfect for inside buildings or close range outside where you need a big field of view, and bright enough at 4000 lumens .
The bumps on the front are something super tough for breaking car windows etc - so I guess aimed at first responder types. I quite like the double clicky tail switch. One is a really solid on/off click and the other cycles between light levels.
It has two modes, I use it in the everyday mode where it remembers the light brightness from when you turned it off. There also a hard core mode where it always turns on in max.
The hard plastic holster has a hole in the bottom, which I assume is to avoid melting it with the 4 x 4 x CREE XP-L2V6 leds, but I have occasionally just turned it on in the holster for general lighting if I needed both hands.
Since it's quite easy to pull it out of the holster, I do have a slight worry that it will come out by itself if I'm clambering around somewhere - but it never has yet. The holster is intended for clipping on those massive duty belts - it would swing around a bit otherwise. I have a vague recollection it came with some clips to use on narrower belts but perhaps I've thrown them away.
The 21700 battery it needs is a weird Nitecore one with positive and negative contacts each end. I wasn't wild about that, but in practice I never carry spare batteries, so they can be weird or built in and it's no particular problem. If you really hate this idea, there is an optional caddy for 2 x cr123s - but less brightness and lower run times.
Oh, that thing with the battery would piss me off. I have a burning hatred of nonstandard batteries. I don't often carry a spare, either, but I an much more interested in knowing that in 2-3 years when the original battery is toast I can just take another one off the shelf and move on with life.
This was my exact view a few years ago, and still a bit now. However, all the lights I own that take standard 21700s don't get used by me because modern torches have improved so much. I'm gambling that by the time I can't get these batteries (which will be a while since Nitecore is a reasonable company) that light or battery technology will have moved on so much that this flashlight (currently excellent for it's purpose) will be just be ewaste anyway.
This proprietary battery that Nitecore uses for all their latest generation tactical flashlights is the reason why I don't buy or recommend them. It would have been easy to avoid these batteries.