Chris C.wrote a review of MSR Guardian Purifier System on February 21, 2016
Familiarity: I've used it several times
The system is extremely easy to use while in the field. You unravel the hose which wraps around the housing of the Guardian and then just drop it right into your water source. From there you can attach a Nalgene or I use the Dromlite for backpacking. It's a bit heavy at about 1 lb., however I think the peace of mind is worth it. I also don't have to deal with the slow output of Sawyer every time I take a drink, which drives me nuts. Plus this is actually a purifier and is blocking viruses where others are just filters and don't block as many nasties. With all of these new viruses coming out I think it's becoming essential to actually purify the water.
MSR has great customer service and builds great products. It's great to have an all in one solution for purifying water.