Wedge mouthpiece names are based on the mouthpieces from other standard brands that they most closely resemble. For example, a Wedge version of a Bach 3C trumpet mouthpiece would be a Wedge B3C. A French horn mouthpiece similar to a Laskey 80G is called a Wedge L80G. The names of trombone mouthpieces mostly follow Bach sizes. A Wedge version of a Bach 7C is simply called a Wedge 7C.
The sizes of Wedge French horn screw rims follow the usual convention of being named based on the inner diameter of the rim in mm, plus a letter to indicate rim width.
For detailed information about sizing for specific instruments you can visit the following links.
The unusual shape of the Wedge means that the dimensions of conventional mouthpieces can only be used as a starting point in selecting the best mouthpiece size. When dimensions are listed the number usually given is a "functional" diameter which is a combination of the long and short axis of the rim oval. The Wedge will feel different than your regular mouthpiece. In choosing a Wedge it is therefore important to concentrate on finding a mouthpiece that out performs your conventional mouthpiece, rather than one that feels similar to it.
More Even Response
The Wedge mouthpiece in most cases increases the range available to the player. It does not do this the way a shallow or small mouthpiece does by producing a bias towards upper register performance. Instead it provides a more even response in all registers of the instrument. The spread between the lowest, fattest note and highest note that can be played is increased.
Depending on the characteristics of the Wedge mouthpiece selected, the improved performance in either the upper or lower register may be more evident at first. In some cases the lower register is fuller and easier while the upper register is unchanged or more challenging. This almost always means that a change to a smaller or shallower Wedge will shift the mid point of the range up and return lower range performance to the same level as a conventional mouthpiece while providing improved upper range performance.