The chief attractions of these devices are ease of use, low cost and operational reliability due to their simplicity. The sets consists of two components, a transmitter and a receiver. Using the indicators on the receiver, a diver can easily return to any location or object marked with a transmitter. To aid in the return to a boat, the transmitter may be lowered from the boat or attached to the anchor line. To serve as a distress beacon, the transmitter can be carried by a diver, to be activated when an emergency occurs. Any number of receivers can be used with one transmitter, allowing a group of divers to use the system. Great for Dive Club, Dive Boats, or Resorts. Must have Item for Spearfishing and Hunting. Sold as a set or indivisal units.