There’s simple (Steripen’s other products) and then there’s ultra simple (the Ultra). Just swirl the UV wand in a liter of water for 90 seconds and the OLED screen shows smiley (success) or sad (try again) faces. Ultraviolet light neutralizes water-borne nasties. The display will even let you know if the bulb needs to warm up (if so, place it in an inside pocket next to your body).
The Ultra has an internal battery that juices up via the included micro-USB cable, which can be plugged into a computer, solar charger, or the AC wall adapter (also included). One charge nets about 50 treatments, which was enough for our tester to filter water for a group of four on a three-day trip in Zion National Park. $100; 5 oz.; steripen.com