It's a Schaller part, called a "
Sure Claw". That hex head bolt you see in the center of the part attached to the body is internally geared so by turning that, both spring tension screws get turned equally at the same time. It's an easier adjustment than trying to angle a screwdriver in to the traditional wood screw attachment scheme. Also, it allows for fast adjustment if you're the type who's changing string gauges all the time and need to adjust your spring tension to keep the bridge plate level (although, I'm not sure I'd exactly call that an under-served market, especially for Floyd users).