Concerning wrist weights, you may have seen many bodybuilders whose wrists are wrapped around heavy duty straps. Those are known as weight lifting wrist straps. Wrist straps are usually applied to help bodybuilder in extending their grip on certain workouts such as heavy barbell shrugs and shoulder side rises.
There are many names for these weight lifting equipments. Here are few names that you might have heard about the wrist weights as lifting straps, weight lifting straps, power straps, power lifting straps, dead lifting straps, deadlift straps, hand straps, training straps, weight straps and etc.
Wrist weights have non stretching material that is "noosed" around your wrists and the rest of the material is wrapped around the lifting bar to help you in handling the weight. Their main function is to keep the bar in your hands when lifting heavy weights.