Compared to most chinese light manufacturers HDS Systems just goes that extra mile with their lights:
- the glass lens is around 3mm thick and is held in place by an o-ring on both sides for shock protection
- there are springs on both sides of the battery tube preventing battery crush when the light hits something, the springs are also not just springs: they have a flat piece of metal with 3 dots on it for better contact and to prevent battery crush
- the anodisation is extremely thick
- there are no exposed sharp edges on the outside of the light
- the walls and the bezel are very thick, noticeably thicker than those of most chinese lights
- the lights don't have a normal switch, they have an electronic switch, which doesn't wear our (rated at 1.000.000 million presses), they do this so that the high current going through the led, battery and electronics doesn't go through the switch like on most lights
- the battery is protected from over-discharge -> this is an often pverlooked feature which I find very important, it allows you to fergot the light when it's turned on and even let others handle it for extended periods withoiut risks -> when flashlight causes its battery/s to explode you can't really call it robust
-there is also a reverse polarity protection meaning that you wont destroy the driver when you put a battery in the wrong way
- the electronics of the light are potted, this means that they are shock protected and water proof -> potted means that they covered in a glue-like compound which you can't really remove
- the lights have a thermal protection for the led -> this means that they wont burn up on you when you aren't paying attention or lending the light to someone else
-> I think there should also be a thermal portection for the battery
- the standard bezel is made up of thick stainless steel which is much more impact resistant than (even anodized) aluminium -> some of the other manufacturers also so do this on some of their lights (Jetbeam, thrunite ...)
- the parts are made with very narrow tolerances (this is the reason for Henry's problems with the parts suppliers) -> everything just fits perfectly, when there is nothing loose it's unlikely something will break
- the lights (not sure about the Rotarys) are waterproof up to 20m (static) instead of the usual 1m
- the lights are actually emp-proof, if all arguments fail use this one
(although useless for most people)
All in all thats a pretty long list, wouldn't you say?