I'm not 100% sure exactly what this is... however based on my limited knowledge of scuba diving equipment, I'd say it's a dual manual add valve (MAV) for a closed circuit rebreather (CCR). I could totally be wrong, so selling AS IS, NO GUARENTEES, NO RETURNS. Appears to have two buttons, 3 hose connections and a belt clip, so you know it's going to be awesome. Come and get it!
