This category includes all heavy infantry regiments of the Imperial Guard.
"Heavy Infantry Regiments are marked out by the personal equipment of their Guardsmen. Almost all troopers in a Heavy Infantry Regiment will be equipped with heavy armour, such as carapace armour or a more exotic design unique to their world of origin. Similarly, weapons issued will be of a 'heavier' nature with a preponderance of plasma or similar high-end energy weaponry issued to specialists and teams. It has been known for all troopers in a Heavy Infantry Regiment to be armed with hellguns instead of the standard Guard weapon, the lasgun." Lexicanum