These silnylon pack rain covers are ultra-lightweight and will protect your pack and belongings from harsh weather. The entire cover is made from 1.35 oz. silnylon to shed rain, snow, ice, and about anything else the skies will throw at you. The cover secures around you pack with elastic draw cord and cord lock for a super tight fit. Many colors are available. All seams are double sewn for durability.

The cover will take up little space in a pocket and weighs almost nothing. Comes in 6 different sizes to fit about any pack. Small stuff sack that attaches to the pack cover is included. 
XSmall: Less than 1700 (in3 pack)  2.1 oz
Small: 1700-2400 (in3 pack)  2.1 oz
Medium: 2400-3600 (in3 pack)  2.3 oz
Large: 3600-4600 (in3 pack)  2.8 oz
XLarge: 4600-5600 (in3 pack)  3.2 oz
XXLarge: 5600-6500 (in3 pack)  4.0 oz
(in3 is cubic inches) The capacity is only approximate capacity of each size. Capacity can vary due to shape of pack and external attachments. If you order the wrong size, then you can return it for the proper size.