The Racer Medium is basically leaner, meaner and racier than the standard Racer. Due to it's very stiff and short arms it modulates power better than any other brake.
The Racer Medium features a bridge piece that runs between the pivots allowing it to mount to frames with a single brake mounting hole above the tire. An option is given for a shorter recessed bolt to work with modern frames, or a longer non-recessed bolt that works with older frames. Because of this feature, the Racer Medium is a medium (or "standard") reach brake with a range of 47mm to 57mm. The arms allow enough clearance to fit a 45mm fender and a 32mm wide tire, and the brake will not pinch the side of the fender like dual pivot brakes do.