CamelBak Men&#39;s ShredBak 72-Ounce Hydration Pack, White, Small Breathable, comfortable mid- layer vest with integrated compression compartment to keep Omega reservoir stable while riding, skiing or on the chair Chest pocket makes storage of bite valve easy Insulated tube cover and close to core positioning enhances freeze resistance Soft Shell vest can be worn with or with without the integrated reservoir liner Vest weight (sz med) with filled reservoir is 5.69 lbs