How much water is left in your hydration pack? CamelBak's Flow Meter answers that question by measuring your fluid intake and expenditure. This useful gauge integrates into your reservoir's hose and is small enough to stay out of the way, but large enough to read easily with a quick glance. Now, you'll know how much liquid remains, helping you to better plan your rides. Another handy setting is the hydration goal feature, which is indispensable for maintaining a consistent fluid intake, therefore helping you ride your strongest. Never be surprised by your last sip again.
Wheel World has the Flow Meter on sale for $19.99 (it usually sells for $35). Click here for their deal.