A fine distinction
The softness of a wool garment is affected by the fineness of the fibres used in the yarn. The thicker the fibre, the less flexible it is when it comes into contact with nerve endings in the skin, potentially causing irritation.
By definition, superfine wool is soft and prickle-free. It can be spun as exceptionally fine yarn and woven or machine-knitted into smooth, lightweight fabrics. Such exclusive fabrics are traditionally used for the finest tailoring, for next-to-skin wear and for occasions when only the best will do.