I've had some experience with body micing, and no maker of security or surveillance radio transceivers locates them in the middle of the back. Ear prompters and body mics universally use a box with a clip intended to be fastened to the waist or placed in a breast pocket. For a one-way receiver "ear prompter" (what the conspiracy theorists are presumably talking about), there are many units that fit entirely in the ear, obviating the need for a control unit entirely. I highly doubt that this kind of device would assist any person in a debate: unless you are reading a memorized script that is also being prompted in sync, the result of hearing a person talking while you are also attempting to speak is not very helpful. The horizontal line and bulge, however, are consistent with the horizontal "drag straps" used on some kevlar vests, specifically those intended for use by dynamic entry teams. The strap is typically heavy duty nylon, linked to a harness on the interior of the vest, and intended to allow a teammate to pull a man's weight. In situations where the entryway is a single door, should the lead team member be hit, the adjacent man can drag the wounded man rearward along the ground with one hand while providing suppressing fire with the other. Dynamic Entry vests are typically Class IIIa plus, with front and rear ablation plates, and very bulky.