KT Custom Mouthpiece RT4 Back Bore

This is the RT4 backbore from KT Custom Mouthpieces.

This backbore offers a resistance level that is easy to switch to for those accustomed to the #10 backbore (standard backbore for C cups).

RT stands for Reverse Taper, named after the reverse taper that enters the throat section from the cup side, unlike the usual direction.
*The throat narrows from #27 to #29 within this backbore, making it compatible with standard tops like the #27 Warburton.
You can easily understand the structure by visiting the KT website.
→(https://ktcustommouthpiece.com/lead-trumpet-backbores/)

It provides a uniform blowing sensation and is very easy to play.

It is compatible with Warburton specifications, but there is a possibility it may not fit depending on the manufacturing period.
Please be aware of this in advance.