An HID flashlight uses a technology that is almost the same as of fluorescent and flash bulbs in which an arc is created in a gas-filled tube which causes a metallic vapor to light up. This kind of lighting needs ballast and other circuitry making it more expensive than incandescent flashlights. The ballast is the part responsible for limiting the amount of current in the flashlight's circuit and is the one that establishes the arc so that the flashlight can light up. HID flashlights are flashlights that produce very bright light. It can produce a light that is the same as a car's headlight while using the same energy being used by an incandescent flashlight, which makes it a total energy saver. However, since the ballast needs to warm to produce the light, it may take a couple of minutes before the flashlight lights up.
There are many uses and designs for an HID flashlight. One is the headlamp which is normally seen attached in a helmet. This kind of flashlight is often used in hands free operations. This increases the mobility of the person using it. It has been used in mining for many years and other jobs that require the same device. A penlight is another common design. As its name implies, this is a small pen-sized flashlight that are mostly used by doctors for their patients. They can also be used in search and rescue operations especially if the location is underwater or a thick jungle where only limited light can get through the canopy. It perfectly provides the light needed to locate survivors and other things. HID flashlights can also be seen attached to high powered weapons that are used by soldiers and law enforcement officers. You can also use it for the most basic of purposes, like when the main power in your home shuts off, though such mundane uses often don't justify the expense of an HID torch flashlight.
There are 10W, 20W and 35W HID flashlight available in the market. The 35 watt HID flashlight is most common in terms of availability and functionality. In some stores, they do not sell the flashlight itself or the battery and charger alone. They sell it by kit which good is you need a whole new set. Often, this comes in a very nice and rugged carrying case because they know that if you're spending the money for toughest & brightest light on the market, then you're going to need some protection for your investment. This isn't very practical if you have an existing one and you just need to get some new parts or accessories for it, and sometimes you'll have to contact the manufacturer directly for such replacement parts.
HID flashlights are by far the best lights on the market, and good luck finding a cheap HID flashlight; they are difficult to come by. Expect to spend at least a hundred dollars, but whatever HID flashlight you decide to go with, it is important to consider your situation, the environment where you will be using it and of course your budget.