Worn on the arm and head every day. To remind them.
One of the boxes is attached to their arm, by their heart, and the other to the head, in order to remember that the truth they felt deeply in their heart was a true, logical and real thing.
Their emotions were one with their logic.
With those simple black straps and boxes, it reminded them that no matter how insane the world claimed they were, no matter how much they were told that everything they felt and thought was out of sync, was wrong and bizarre and crazy, they would have a sign, an anchor, that reminded them of the truth.