Trust Sweet Iron Dee Bit Dr. Bristol
The D-ring cheekpiece consists of two rings that are shaped like a D. As the rings cannot move back and forth, this cheekpiece offers more stability but also lets the rein aids come through more directly. The D-shape gives more side pressure (against the cheek), making steering easier.
The Dr. Bristol mouthpiece is a double-jointed mouthpiece with a flat middle section. Due to the shape of the mouthpiece, the pressure is evenly distributed between the middle and the side of the tongue upon tilting.