Waterpik Cordless Express vs Waterpik Cordless Gem 5100

The Cordless Gem 5100 is the better flosser for daily home use. It has a rechargeable battery rated for up to 9 weeks per charge, a 7 oz reservoir that gives about 60 seconds of flossing, two pressure settings and 1,573 pulses per minute. The Cordless Express runs on three AA batteries and holds less water, so it needs more refills and battery swaps, but it is smaller, lighter and easier to pack. Both are Waterpik units accepted by the ADA, and owners of both praise the gum results; the Express draws more complaints about weak pressure and battery drain.

• Choose the Cordless Express if you want a compact, battery-powered flosser for travel, a small bathroom or shower use, and you don't mind swapping AA batteries.
• Choose the Cordless Gem 5100 if you floss daily at home and want a rechargeable battery, a larger reservoir and two pressure settings.