Matthew K. wrote a review of Hydro Photon SteriPEN Adventurer Opti on November 25, 2011
When I'm not 100% sure, I use my Steripen rather than my Katadyn hiker pro. Steripen also deactivates water-born viruses, and so far I haven't gotten sick after using it. It definitely doesn't improve the taste of water nor filters things(!) out, but with clear water, you can be relieved to know that you're bacteria/protozoa/virus free! It is super easy to operate, and it also works as a backup torch. You definitely go for Steripen, especially when you're planning international trips. Long story short; awesome! I like it!