SAPs* have limitations, when attacked by unusual or high velocity bullets, they fail. HAPs** are introduced in front of SAPs, normally in an integral front and back pocket of the vest outer cover. These HAPs are normally constructed from monolithic ceramic tiles backed with high-energy impact absorbing material which maintains the integrity of the ceramic HAP under attack. Polyethylene 'plates' made from Dyneema and Spectra are also produced, however these armours are not yet capable of withstanding attacks that can be stopped in ceramic HAP. AK armour piercing incendiary [API] bullets penetrate these armours easily.

* SAP - Soft Armour Panel
** HAP - Hard Armour Panel