Underwater slates are useful when there is more detailed information to communicate or remember. A large variety of designs are available. Some clip to the divers BCD, some fit into pockets, some integrated with other units such as the compass and some attach to the wrist or forearm with bungee straps. The basic parts comprise just an underwater pencil attached to a plastic board by a short tether, and a way to attach these to a convenient point on the diver's equipment. Slates are particularly useful for information that must be written down prior to a dive and referenced during the dive: elements of the dive plan (depths, durations, decompression schedule) or a drawn map of the dive area.