From Halopedia, the Halo wiki
The CH252 helmet is the standard issue combat helmet worn by the members of the UNSC Marine Corps, UNSC Army, and UNSC Air Force; it is an integral component of the Marine and Army Battle Dress Uniforms. It has been in service since the Insurrection. Ushuaia Armory was involved in the development of the helmet, though Misriah Armory is known to manufacture it, either in lieu of or in addition to Ushuaia.
The standard helmet weighs 4 lbs (1.8 kg). When worn with the Marines' M52B body armor, the helmet is typically painted olive drab, though when worn with other body armor models, the helmet is painted to match the body armor. Within the Army, the helmet is generally painted tan, dust gray, or olive drab; medics' helmets feature a caduceus. Air Force pilots' helmets are painted dull brown, similar to those of many Marines. In the Marine Corps, the name of the wearer is sometimes stenciled on the back of the helmet, though this is not always the case.
The helmet can be outfitted with a heads-up display eyepiece or ballistic goggles that can be polarized either orange or black, as well as a boom microphone and a tactical flashlight. The helmet can be fitted with an accessory clip which can be used to mount a night vision device. The basic Army configuration of the helmet features a chin strap, though this is typically not worn by Marines. Balaclavas are often worn with the helmet, especially when operating in frigid environments, though they are occasionally worn in temperate and desert climates.
UNSC personnel have created several nicknames for the helmet, including "coconut", "lid", "can", and "pasta shell".
The ECH252 is an enclosed variant of the standard CH252 helmet. The helmet can be fully enclosed and environmentally sealed, featuring either a polarized or unpolarized visor; this sealed configuration is the basis of the Beta-5 Division's military police helmet, which is a shared asset among the branches of the UNSC Armed Forces. This version can be used with vacuum suits during extra-vehicular activity. It is also utilized during terrestrial combat as part of the Marine Corps' Atmospheric/Exoatmospheric (A/X) BDU, which can provide protection from the environmental hazards caused by glassing. This variation is standard-issue for the Army's UH-144 Falcon and YSS-1000 Sabre pilots. The Beta-5 Division's MP helmet can also be used in conjunction with MJOLNIR armor. When the user speaks with the non-MJOLNIR variant, the mouthpiece that encloses the helmet moves in tandem with the lower jaw.
New Mombasa Police Department model
A variation of the CH252 helmet was worn by the officers of the New Mombasa Police Department. This version featured a large blast shield to protect the wearer from small arms' fire and presumably from shrapnel and secondary explosions. Like its military counterparts, the NMPD's version of the CH252 could mount a boom microphone.
List of appearances