I received the Crazy Cap 2 at no cost for an honest review.
First and foremost, it's important to understand what this device is:
It is a bottle with a cap that has a UV light that illuminates and kills 99.999 percent of bacteria and viruses.
It works because this type of UV light alters the genetic material in bacteria and viruses, and renders them dead.
What does it NOT do?
This device does NOT remove odors, sediment, hardness, minerals, and does not include any sort of filtration.
With that being said,
The Cap charges through a USB cable and can also be used to illuminate any surface (not skin) and kill bacteria and viruses on them, by slowly shining the UV throughout whatever it is you are sterilizing. For example, you could take the cap and turn it on, and slowly hover it over your phone to kill bacteria and viruses.
The bottle holds 17oz/500ml, and is of aluminum. The Cap is also aluminum.
The Crazy Cap 2 is not dishwasher safe, and the warning label on it says "content temperature must not exceed 130 deg F"
Basically, don't try to boil water in the cap and you should be ok. Also, don't pour scolding tea inside of it.
What does this do?
It allows you to remove microbes from water and ensure you don't get some bad water poisoning via a bacteria/microbe/virus.
This will not lower your water hardness, and it will not alter taste, so keep that in mind in case you're taking it hiking and plan to drink from a natural water source. However, for survival purposes, it's practical.
The cap has different LED colors to indicate its charge level, so that was a handy feature.
I used the cap multiple times in one day, stored it for 5 days or so, and then the battery needed to be recharged.
I think this device performs well (though I wasn't able to test the virus levels or any real "before and after" tests), but I am going by what I know about UV lights and their effect on water.
On those grounds, this is a practical bottle/cap, I think it has potential to do even more, and I commend CrazyCap for designing something that can ultimately save lives.
I would characterize the CrazyCap 2 as more of a supplemental device along with some sort of filtration, to provide safe and good-tasting, sediment-free water. I wish it did have more features along those lines, but I do understand the costs associated with increasing features.
I do recommend it, though please be informed of its capabilities and limitations when it comes to potable water.