Rio Karma 20GB = 2.7"(l) x 3"(w) x 1.1"(h) = 8.91 cubic inches
iRiver iHP-120 = 4.13"(l) x 2.36"(w) x .75"(h) = 7.31 cubic inches

The iHP-120 is almost 20% smaller than the Karma!