The DH-133A Combat Vehicle Crewmember Protective Helmet was developed by Gentex Corporation as an upgrade to the DH-132® and DH-132A models both of which were type classified and adopted as the Standard A for U.S. Army personnel.

The DH-133A retains the compatibility of the DH-132 and DH-132A models with field components such as binoculars, protective masks, and vehicle instruments while offering improvements in the areas of comfort, sound attenuation, and helmet retention and stability.

The DH-133A helmet has five major components: a ballistic helmet shell, an energy absorbing liner, a thermoplastic liner (TPL®), retention assembly, and communications assembly. Ballistic, impact and lateral protection are provided by combining the high strength protective materials of the shell, energy absorbing liner, and earcups. The TPL is preformed and will fit a majority of head sizes, and can also be custom fit to individual head shapes. The retention assembly features separate adjustable chin and nape straps and permits earcup rotation to enhance fit and noise attenuation. Additional proprietary design features of the DH-133A helmet include a raised inner ring on the earseals which reduces outside ambient noise while improving headset communication, and an earcup tension spring.