Some of the questions answered below
Saxophone Mouthpiece Breakdown
Choosing a Mouthpiece
For sax mouthpieces the common rule is that softer materials produce a darker sound with less projection, while harder materials just the opposite (brighter and more projection). From plastics to metal though, you have a wide range of options to choose from, allowing you to truly customize your sound.
Most common for students, plastic mouthpieces are extremely durable and quite affordable. The only real compromise is the bright sound that can be challenging to focus.
Ebonite (Hard Rubber)
Warmer and more focused than plastic, ebonite is often used by classical and jazz musicians who don't need to worry about edge or projection.
Preferred mainly by jazz and outdoor musicians, crystal has a strong projection and an equally bright sound. Quite fragile though, a soft, dependable pouch is definitely recommended when not in use.
Though not the most widely used choice, wood offers the warmest tone of all the materials listed here. If does produce less projection as a tradeoff, and can also be less stable than rubber or plastic.
If you are leaning towards metal, most are made from plated-brass. Used in a variety of styles, the most common is gold-plating but you'll also find a mix of others that vary in tone as well.
Of all the metal mouthpieces, stainless steel has the brightest sound and the most projection.
Facing & Tip
The facing is where the mouthpiece meets the reed, and directly correlates to the opening of the tip. As a rule of thumb, the longer the facing, the smaller the tip (and the reverse for a shorter facing), which dictates a number of other factors including reed strength, focus of sound and timbre, projection and the degree of "free-blowing". For quick reference, see the chart below:
What is a Baffle?
Simply put, the baffle is the part of the mouth piece on the opposite of the window and it dictates the "edge" or "bite" the mouthpiece displays. It's also important to note that the higher the baffle is on the mouthpiece, the brighter the sound and the more projection it will produce, while the lower the baffle, the more warm and mellow the sound will be.