From Hammacher Schlemmer:

In tests conducted by the Hammacher Schlemmer Institute, this allergen barrier was rated best over other bedding for softness, shrinkage, allergen protection, and strength. The bedding scored highest for softness and shrinkage and was highly rated for allergen protection and strength. Ten panelists commented that the bedding had “a soft, durable, luxurious, and high thread count feel” and that “the sample did not shrink.”

The mattress encasement go as deep as 15″ so, that it throughly serves as barrier  and not simply just a protection for the top of a mattress. Dimenstions: 15″ Deep King Mattress Casing. 80″ L x 78″ W x 15″ D.

Via