PROTECTIVE GEAR12-6. Helmets must be fitted properly to ensure they stay on the jumper’s head during deployment of their parachute and during parachute landing falls. U.S. Navy and U.S. Marine Corps personnel will use helmets approved according to sister service regulations and approved equipment lists.12-7. The advanced combat helmet is a modular helmet system that provides ballistic, fragmentation, and impact protection. (See figure 12-1.) This system is compatible with the current night vision devices (NVDs), communications packages, and chemical defense equipment. The outer rim of the helmet shell of the ACH must be inspected for any sharp or protruding edges that may cut or fray a jumper’s USLM upon exiting the aircraft. Sharp or protruding edges will be taped with pressure-sensitive adhesive cloth. The ACH has the following characteristics: The helmet system provides nine millimeter (mm) and fragmentation protection within a spectrum of environments (cold down to -40 degrees Fahrenheit; hot up to 140 degrees Fahrenheit; salt water; fresh water; petroleum, oils, and lubricants; and so on). The ACH allows maximum sensory awareness for the operator, which includes an unobstructed field of view and increased ambient hearing capabilities. The helmet’s retention and suspension system provides unsurpassed balance, stability, and comfort. This unique system provides for proper size, fit, and ventilation. The pad suspension system provides superior impact protection throughout all operational requirements.