Features:

• 100% waterproof, seamless design.
   
• Shock cord draw string cinches tight around your pack.
   
• A lightweight strap clips underneath your shoulder straps to ensure that the pack cover will never blow away in a gust of wind!
   
• Available in 1.3 oz/sqyd Silicone Nylon or .6 oz/sqyd Cuben Fiber. Sil-Nylon is a bit more durable (but also twice as heavy) and may be a better choice if you plan on doing alot of bush-whacking in the rain. Cuben Fiber is plenty durable enough under normal conditions.
   
• A stuff sack is now included in the price and weight. The stuff sacks are about the same size as a "Rock sack" and can be dual purpose.

Small - Up to 2000 cubic inches.
Fits the Zero, Zilch, Blast 20 and other similarly sized packs.

Medium - 2000 to 3500 cubic inches
Fits the Z1, Blast 26, Blast 32 and other similarly sized packs.

Large - Fits 3500 to 5500 cubic inch packs

The covers are sized to fit the specified backpacks at maximum capacity, however they may not fit if bulky items are strapped to the outside of the pack.

Color:
The Sil-Nylon pack covers are currently available in a "normal" blue color which is a bit lighter than the dark blue backpack pictured to the right. Cuben pack covers are white or green as shown.