The BOB punching bag is the shape of a man’s torso and head, but without arms. It is intended primarily for use as a training aid in martial arts. The striking surface is made from a high strength polymer, and the interior is filled with a solid core urethane foam. The BOB training bag is, therefore, a solid fill punching bag, and while the skin has a little bit of give, hitting it can be hard on the hands and on the joints. The face and head, in particular, is hard, though this may be intended to emulate the same hardness in the human body.
The base comes empty and has to be filled to give the bag weight and to keep it in place. It is designed to be filled with either sand (available from a local big box hardware store) or water. Either works, though sand can be better as it ends up being heavier, and creating a more stable base. When using sand, the bag will end up weighing 250 lbs. It should probably be put where you intended to use it before filling, as it will be difficult to move once the base has been filled. Attaching the bag to the base will probably also require some extra hands to hold it steady while it is screwed down.
Though this bag is made of materials strong enough to last for quite a while under proper use, it can be easily destroyed if it is attacked improperly or unsafely. The materials that hold the body to the base are held by a set of screws, which can tear out and rip the core and covering. The screws and brackets holding the body to the base can also come loose after several workouts, and require additional tightening. Adding some Loctite or a couple of lock washers to these screws usually solves this problem.
For true martial arts training, a similar dummy with arms and legs to practice a wider variety of techniques might be nice. However, this works well for its intended use, offering a somewhat more realistic target than a simple heavy bag, allowing a practitioner to understand precisely how to strike a human target. Someone more interested in using a bag for a more fitness focused workout, this is probably not the best choice.
This bag is probably best suited for personal use, or use in a dojo or other organized martial arts setting. When used correctly, with good technique, it can last a good long while and be a good training aid. When used improperly, its lifespan can be shortened dramatically. It is an expensive option for a heavy bag, but it offers many advantages a regular, cylindrical heavy bag cannot.