There are two basic styles of belts available for hard weights. The most common is a 2-inch nylon belt. Nylon is used because it's strong and does not deteriorate in water.

Nylon does not stretch, so if you're wearing a wetsuit, the belt may become loose as you descend and the wetsuit compresses. To prevent the belt from slipping off or rotating, be sure to tighten the belt as you descend.

Rubber belts are also available. These are called "compensating" belts because the rubber contracts as the wetsuit compresses. This maintains a proper fit during the dive, and eliminates the need to tighten the belt as you descend.