We now offer 2 sizes at the same price. The small size (12" X 6") is about the size of a small loaf of bread and great for my clothes bag or my small summer sleeping bag. The large size is aprox 17" X 8" and great for a food bag or larger sleeping bag.
I've been using mine for over 2 years of hard use and it's held up well. Sil Nylon is a ripstop nylong that's been impregnated with silicon.
It weighs 1.1oz per sq. yd.! (extremely lightweight) Yet the silicon makes it waterproof. The seams must still be sealed however. I do this to mine by using silicon caulking from a hardware store and rubbing small amounts into the seams. (its much cheaper than buying an $8 tube of special sealant)
We have a big selection of colors right now and it's a good idea to have a different color for each stuff sack so you can easily tell your gear in the dark.
Request your colors but keep in mind they change periodically. ENJOY!
Small size: 7/10 of an oz.
Large and Tall: 1.1 oz.