Carapace Armor
Carapace armour is basically Flak Armour LV2. A bit tougher, and a bit more expensive. Usually given to commissars and stormtroopers. A step down from the Void Armour of the Great Crusade era. It is currently the best armor that non augmented humans outside of the Sisters of Battle and Inquisitors can get their hands on. Rarely it will also be worn by Lost and the Damned or a well equipped PDF.
Like Power Armor it has Ceramite molded into it's plates. This also makes it much heavier and will fatigue the wearer much faster than flak armour or power armour given that it usually lacks any kind of assisted movement systems, though that isn't always the case as semi-powered examples do exist.
The protection provided by a set of carapace armour varies a lot from story to story, as you'll frequently hear of normal bolter bolts punching clean through power armour and thus should go through carapace like it wasn't even there, however on the tabletop now carapace offers some protection from the likes of heavy bolters, power mauls and autocannons, and to a lesser extent even Hellguns, Inferno Bolters and Sternguard Bolters.