Through the letter box today popped my As Tucas roll top dry bag. It’s 50x60cms, weighs 28g and cost €40. I’m intending to use it as a rucksack liner. Currently I’m using an Exped XXL normal weight roll top which is a bit larger but weighs 115g. I normally pack all my sleeping gear and clothes that I won’t need during the day in a roll top bag at the bottom of my rucksack. The Exped is actually a bit too large for that purpose, hence a slightly smaller size for the cuben liner.
As with the stuff sacks I bought from AsTucas, the workmanship is good. The roll top seal doesn’t have a stiffener (to save a bit of weight) but seems to make a pretty good airtight seal. Marco has also provided a small strip of cuben backed with adhesive should any repairs be necessary.
I had been mulling whether to buy a thin gauge nylon roll top bag, which would be considerably cheaper but about double the weight. However, I’ve read a few negative reports about the durability of the coating of these sacks. Indeed, the Exped pump sack that came with my lightweight down mat has started to show signs of de-lamination.
While a weight saving of 87g is useful rather revolutionary, I am confident that cuben is very waterproof and should keep my sleeping bag and spare clothes dry. (Addendum: just to clarify, this was a custom order)
Disclosure: I paid for this with my own money and have no relationship with As Tucas, financial or otherwise.
blogpackinglight 
Tempting.
Too late for Santa’s Sack.
But I have a birthday in March.
First there is the results of the scan on the knee. Scan in 2 weeks.
Wow, thats a lot of weight out of your wallet to save 87gr out of your sack. But if you can, why not.
Cuben is never cheap but it is properly waterproof and the sack is the right size.