SRD:Phasing

Phasing: The wearer of this kind of armor can move through wooden, plaster, or stone walls, but not other materials. The wearer can call on this special ability as a standard action. When the phasing ability is active, the wearer can pass through a wall or some other kind of appropriate object for a total distance of 60 feet per day (see below), breaking this distance up into several smaller passages or one long one, as desired. A wearer who exceeds this daily distance limit while inside solid material is ejected from the material at the point of entry, ending up prone in front of the now impassable barrier.

Phasing through a wall that separates two adjacent squares on the grid counts as 5 feet of distance. Phasing through a wall or barrier of any greater thickness counts as a distance equal to the barrier’s thickness plus 5 feet. feet of distance.

Strong psychoportation; ML 13th; Craft Psionic Arms and Armor, psionic phase door; Price +65,520 gp.