The uppercut bag is essentially a heavy bag that is mounted on a wall or sometimes a beam. Usually the bag is mounted so that it is longer horizontally (as opposed to a normal heavy bag which is longer vertically because it is suspended vertically.) As the name suggests, this bag is used for practicing uppercuts. The way the bag is mounted allows for a boxer to hit the underside much more readily than with a normal heavy bag.
While the uppercut bag is mainly thought of as the tool of choice for practicing mainly uppercuts, it can also be an effective tool for practicing hooks. On a heavy bag, you may have the experience of having your hooks glance across the front of the bag instead of having it land solidly on the side. However, if you are using an uppercut bag, the left and right sides are usually a bit more flat. Therefore, it is easier to land flush and “feel” your punch land correctly.
To use the uppercut bag most effectively, overemphasize uppercuts and hooks in the combinations that you choose to throw. Move side to side as you throw straight punches and end the combinations with a barrage of hooks and uppercuts. For example, if you start on the right side of the uppercut bag, throw a jab on the right third of the bag, move to the left, jab at the center of the bag, move again to the left and throw a straight right hand the left third of the bag. End this combination with a left uppercut, right uppercut, left hook.
As I mentioned in my article about the uppercut, uppercuts are most often called the most underused punch in boxing. This is a shame, since if landed correctly, an uppercut can be an extremely jarring punch for your opponent to take since the head is snapped up and back. If you are serious about becoming a better fighter, I suggest adding one of these uppercut bags to your home gym and incorporating the uppercut into your offensive repertoire: