The ASHPD is held with a hand behind the weapon, holding the handle/trigger, while the other hand supports the barrel. Material Emancipation Grills will block any attempt to shoot portals through them, as well as reset any active portals should the ASHPD pass through it. Moving objects, or certain types of surfaces, will prevent the formation of a portal (The only exception to this is in the neurotoxin generator in Portal 2). Though considering that fact that portals can be placed on what seems to be standard concrete, and that the device was used in the 1950s by Aperture before the discovery of the moon rocks’s capabilities, it is likely that moon rock is not required for the creation of portals but instead just very effective. The portals can be placed on any surface which is made out of manufactured or refined moon rock and large enough to accommodate them. No matter the distance between them, any object which passes through one portal will emerge from the other and vice versa instantaneously. The ASHPD is a hand-held device which has the ability to manufacture two linked portals.

Chell facing a portal she just created in Test Chamber 04.

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