A little water doesn't deter you from a multi-day backpacking trip, but it can certainly soak your gear if you aren't careful. Slip Integral Designs' Silcoat Pack Cover over your trusty backpack when the clouds start to dump. Built with parachute-grade silicone impregnated ripstop nylon, the Pack Cover comes in three sizes to accommodate anything from an overnighter to a full size expedition pack. A hood and wrap-around adjustable shock cord round out this backcountry enthusiasts' must-have for full wet-weather protection; no more worrying about taking an involuntary bath every time you dig for your sleeping bag.
Ordered the large and it fits my 65L pack with room to spare! I am pleased with the ease of use. It never fails to rain on me when I hike so I used it on my first trip having it. It stayed on my pack just the way I put it on and didn't move for the 7 miles of trail I covered during the rain.