Over-tightening of the DIN retainer by a technician during installation can result in the retainer breaking under pressure, a rapid escape of air from the scuba cylinder, and the regulator detaching from the scuba cylinder. This poses a drowning hazard to divers. The recalled regulators have a brass DIN retainer manufactured prior to June 2006. The recalled Aqua Lung Titan Din 1st Stage regulators have serial numbers lower than 6062501 stamped on the side of the regulator’s body. Recalled Titan/Conshelf DIN adaptors are marked “300 BAR MAX” on the side of the part. DIN adaptors marked “300 BAR MAXI” are not included in this recall.