This one is a single ply superwash merino wool. And so yummy and squishy ๐. I frequently use acrylic yarns though, they've come a long way as far as softness and durability.
Single ply means one strand of fiber vs plied yarns having multiple strands twisted together.
Superwash is a treatment to remove the scales and keep the fibers from felting together with agitation.
Now you know a little bit about yarn ๐คฃ๐คฃ