Some helpful info when considering trumpet mouthpiece specs:

Inside Rim Diameter can range from about 0.500″ to 0.690″. For most players, a comfortable inside rim will be in the middle, 0.630″ – 0.675″ or so. Measuring the diameter of the inside of the rim is extremely variable between companies and between rims. Some companies measure at the high point of the rim, some measure at the top of the cup, and some measure at the point where the rim begins to curve inward. If the rim is very round, it’s even more difficult to find a consistent spot to take the measurement. Use this number as a guideline, not as an exact measurement.

Throat Size, or Bore: most companies consider the “standard” throat size to be #27. This number refers to the size drill used. As throat size increases, the numbers decrease. A #19 throat is extremely large, or open, and a #30 is extremely small, or tight.

The Shank is the part of the mouthpiece that goes into the horn.

The Blank is the external shape of the mouthpiece. “Heavy” blanks have more mass and create a darker sound with more core. “Light” blanks have less mass and produce a brighter sound,