The CBRN Hardened Uplink Module or CBRN/HUL, is an external attachment for ODST and HAZOP helmets.
The CBRN/HUL is available as a helmet accessory in Halo: Reach. The device for the ODST Helmet costs 1000 cR while the one for the HAZOP variant is priced at 2000 cR.
"CBRN" stands for chemical, biological, radiological, and nuclear, and is pronounced "C-BURN". It is the same abbreviation used in real life, hence its association with the HAZOP armor permutation.
List of appearances