The closer a mouthpiece comes to fitting your personal physiology, the greater the results you can expect to achieve. The CSB is ideal if you have thicker, fleshier lips but want a shallower cup that will still let the air through. All Stork CSB series French Horn mouthpieces have a shallow cup depth and an inner diameter of 18mm. They are available in 8, 10, 12, 15 and 18 bore sizes.