Detail 01
16.5mm cup diameter
Middle of the range here. Enough room for a full sound without the air demand of the 17mm 2 sizes.

Independent shopping perspective
A silver-plated 4BW cornet mouthpiece with a wide rim and V-backbore. For players who need endurance over long playing sessions.

Strong match
Consider the trade-offs
What matters in use
Catalog numbers tell only part of the story. These are the details most likely to change how this product feels, sounds, or fits into a setup.
Detail 01
Middle of the range here. Enough room for a full sound without the air demand of the 17mm 2 sizes.
Detail 02
Wide. Spreads pressure across more lip area, so you last longer, but fine flexibility takes some adjustment.
Detail 03
Tighter than the 4.58mm open models. More back-pressure to lean on, which helps stability and control.
Detail 04
Focuses and centers the sound compared to the open backbore models. Less spread, more core.
Detail 05
Slightly firmer contact feel than gold. Some players react to nickel underplating on worn spots.
Final check
Product questions
Straight answers to the questions shoppers most often ask about this product.
The 4 has a 16.4mm cup, 5.27mm rim and 4.58mm open backbore. The 4BW is slightly wider in cup and rim with a tighter 4.27mm throat and V backbore — more focus, more endurance.
No. Cornet receivers take a shorter, thicker shank. It won't seat properly in a trumpet.
It helps if endurance is the problem. If you're still building basic flexibility and slurs, a narrower rim gives more feedback while you learn.
Within this series, B models use the V-type backbore and a tighter 4.27mm throat. W indicates the wider rim. So 4BW is the wide-rim, V-backbore version of the 4.
Reference
The complete catalog record, organized around the decisions musicians make when comparing gear.