Jason Hanswrote a review of MSR Guardian Purifier System on February 3, 2018
Familiarity: I've used it several times
Although a bit of a splurge given the price--there are cheaper options that will generally get the job done--this works, it works fast, and it gives me peace of mind no matter the water source. I like the freedom of being able to go anywhere and everywhere without worrying about whether I will find a suitable water source (if you haven't seen MSR's promotional video for this being tested in the Cordillera Blanca then definitely check it out below; that's what sold me on it and I have not been disappointed). Now my entire group drinks with confidence no matter the water source!