The Uncut 9 was designed as a fat, stubby tool to allow for variable amounts of stretching with some penetration. The gentle curve allows for maximum comfort as well as optimal stimulation of those pressure points if you are using it for fun, too. The square base stands firm for hands-free play. The top side sports some ridges, for visual effect mostly.
For a smaller version, check out the Uncut 7 (shown in a side-by-side with the Uncut 9 in the last photo).