Then Carnihtia Combat bivy is the lightest weight and highest tech bivy on the market. Made entirly from Gore Aridtex Lite, this Gortex is not only vapour permeable but is Gas Permeable as well. That means it will pass moisture and echange O2 and CO2 so you can close it up completely in the worst of weather.
This bivvy offers the best of both worlds - waterproof and light. It protects me from dewy mornings and rainy nights. Why carry a 1.2kg bivy bag from other manufacturers when this one does the job? Built in mozzie net is practical and breathable goretex ensures zero condensation.
I have used this bag on exercises across Australia. I've also used it to enclose my pack for a river crossing. Surprisingly effective as the generous proportions will enclose an issued pack comfortably. Everything got to the other side nice and dry.
If you have the cash and want light gear, this is the bivvy for you.