Whether or not a back belt offers any real protection remains controversial. Studies have reported all kinds of findings. Studies of specific belts and how they compare to one another are not yet available.
An occupational therapist in Taiwan did a study to look at the effects of belt pressure on back muscles. The results of the study suggest that the belt used may make a difference. In this case, an elastic belt with four semi-rigid bars on the back was used.
The belt was positioned to line up with the tenth rib, covering most of the trunk down to the pelvis. Belt pressure could be adjusted with Velcro fasteners that stretched the elastic portion of the binder. The general idea is to help the trunk form a cylinder so that the muscles can work together. The more the muscles contract together, the more the force is transferred away from the back.
More information is needed before any particular type or brand of belt can be recommended over another.