It is 50% merino wool and 50% tussah silk. It is a luxury worsted weight yarn. It is similar to the worsted wool, but has that 1/2 silk that makes it extra nice to work with. It comes in 4 oz and has 250 yards and would be suitable for a needle size of 7-9US.
I chose this particular yarn because I have worked with a similar yarn called Venezia Worsted by Cascade. It is what I made the wine bottle bag out of, which was an incredible yarn. I wasn't able to make a sample out of this one, because I didn't have time. Though I am pretty sure that it would felt similar to the Wool/Silk Single.
It would be ideal for hats, scarves, mittens, or any other project that calls for a worsted weight yarn.