I use this hearing protection in the engine room of a ship with three main engines (2x 6 cylinder in-line with 12 liters capacity, 1x 6-cylinder series with 18 liters capacity) and have even after prolonged stay at full speed (2200 rpm) no problems or complaints. The comfort is also good, even after prolonged wearing of ear protection is not annoying or distracting. Compared to models Optime I Optime II and better noise reduction is noticeable.
