The DH-132B protective helmet is produced in accordance with provisions of US Army MIL-4-44117. The DH-132A and B are the ballistic versions of the standard DH-132 with the primary modification being an Aramid ballistic shell in lieu of the standard epoxy glass fiber shell. All helmets are compatible with the environment in which they are used so that binoculars, NVGs, protective masks and vehicle instruments, can be used and operated without difficulty. Three head sizes are available. Options include the Model 6011 conversational communications unit, a noise-cancelling electret microphone and a carbon equivalent electret microphone, talk-through capability, and active noise reduction. The Model 6011 is designed to provide speaking and listening communications for the user when disconnected from the vehicle communication system and when wearing the helmet and chemical defense mask with an integrated microphone and talk-through feature. The DH-132A/S CVC helmet is an improved version of the DH-132 series, incorporating single sizing, ear cup height-adjustment strap, front brow comfort pad, single nape adjustment, adjustable shell straps, improved ear seals and a spring tensioning device for ensuring adequate pressures.