TheCamelBak174 M.U.L.E.174, the most popular mountain bikingsystem on the market, offers the ultimate combination of organizedand overflow cargo options, including a weatherresistant MP3pocket, plus enough hydration for over 3 hours on the trail. OMEGA153 HydroTanium153 Reservoir with Lifetime Warranty Insulation to keep liquid cool for hours Air Director153 back panel for ventilation Dynamic Suspension153 Harness and removable waist beltmaximize load stability