The round knife also referred to as a head knife, is one of the most versatile knives for leather working. It consists of a large, 1/2 circle blade that is sharp on the rounded portion. Since it has such a large blade surface and cutting edge, it can more effectively cut through thicker leathers than smaller knives.
Head knives also work well for thin leathers and detailed cutting. The maneuverability of the blade edge makes it useful for cutting curves. The blade depth can also be controlled manually to set lines into the leather without cutting fully through.
Round knives come in many brands and qualities. Handle shapes are important too. You want to have one that feels comfortable in the hand, in all the various positions one might hold it while cutting. Given all of the assets of the larger, sharper blade, one must also be very careful when handling and using a head knife. with proper safety and use, it is excellent. This is another of the top leather craft tools to have.