Part of the four-piece Modular Sleep System, the Bivvy Cover is an outer shell that is waterproofed with a GORE-TEX lining.  

They say GORE-TEX is breathable, and technically it is but it can get sweaty if you don't manage your layers.  That said, a bivvy is essential if you don't have adequate shelter otherwise.  

Used condition, you can use DWR wash to help reinforce the waterproofing.  Condition 1 will be lightly used, but not heavily worn.  Condition 2 may need an additional waterproofing.  

• GORE-TEX® waterproof, breathable
  
• Sealed seams
• 2-way YKK® zipper
• Mummy hood for total protection
• Fits military ECWS, intermediate and modular bags
• USA Made
  
• Weighs 3.4 lbs

Please Note: May have DRMO ink stamp