Aside from the density of knots, there are many reasons why fine or high knot density rugs are special. If one were to compare two different rugs of the same design, age, and condition, the kpsi would be the determining factor in which one was the more valuable of the two. However, it is possible for a carpet of lower knot density to be more valuable than one of higher density, depending on other factors such as age, condition, design, and the region where it was produced.