Need the hydration but not the pack? Enter the Camelbak Mens Racebak Hydration Jersey. This sleeveless jersey features an integrated reservoir and an insulated drinking tube for easy hydration during adventure races, trail runs, or century rides. The flat seams eliminate chafing, and the Air Mesh insulated back panel simultaneously cools your back and insulates your water. The streamlined design fits under your cycling jersey or lightweight fleece.