Alternation Hinges

This pair of pairs of hinges can be affixed to any door. The door's handle turns into a turnable handle or knob, regardless of what it was initially. Turning the knob clockwise opens the door that the hinges are affixed to normally. Turning the knob counterclockwise creates a portal between the two doorways that the hinges are attached to (as long as both doors are on the same plane of existence). If the doors are on different planes of existence, a symbol corresponding to the plane of the target door appears on the opening door for the next minute.