Check the listing for details. open Box - Mares Smart Apnea Dive Wristwatch. Condition: New other (see details). Listed at 279.99 USD. Care and maintenance rinse with fresh water after each dive, avoid chemicals, and replace the battery when necessary; refer to the instruction manual for details. Power and battery replaceable CR2430 battery with an estimated 200 hours of diving over a 2-year period.