As long as you are psionically focused, your mind generates a tangible field of force that provides a +4 armor bonus to Armor Class.

Unlike mundane armor, inertial armor entails no armor check penalty or speed reduction. Because inertial armor is composed of psychokinetic force, incorporeal creatures can’t bypass it the way they do normal armor. Your inertial armor can be invisible or can appear as a colored glow, at your option. The armor bonus provided by inertial armor does not stack with the armor bonus provided by regular armor.

Inertial armor also absorbs half the damage you take from any fall.

Augment

When you meditate to regain your power points for the day, you may spend power points to increase the effect of this power. For every 3 power points that you spend in this way, the armor bonus to Armor Class increases by 1. This increased effect lasts for the whole day (until you rest).