Hydraulics LT 2.5 L reservoir is not included but you can purchase that for $42 from Osprey and who would want a used reservoir? Excellent condition. used once. You can find more information about this item online. From the site it says, For quick hikes on local trails, convenient hydration makes stretching your legs-and the miles-a breeze. The Skarab 18-liter is a no-frills hiking pack that is comfortable for moderate hikes and daily exploration, and room for just the essentials so you don't overpack. Features Wide-mouth, bucket-style main compartment opening Front panel daisy chain attachment points Adjustable sternum strap with magnetic bite valve attachment, hose port and Osprey Hydraclip for easy reservoir hanging Underlid zippered mesh pocket with key clip keeps essentials handy.