100% merino wool
Filtes King is the manufacturer, Needful Yarns was the US/Canada distributor. This is the same yarn as the Filtes King Joy, which is not discontinued.
Yarndex says it is plied. It looks like a single ply yarn, but it has two very fine, two-ply strands plied (and nicely balanced) with the lofty single, lending greater strength and some resistance to pilling.
“This stunning self-striping yarn is extra soft to the touch and knits together both beautifully and easily. Joy is currently available in twelve couture color combinations and is also perfect for felting.”