Inside diameter:4.1mm, L/M/S
Outer diameter is about (mm):
S:10 M:11 L:12
The T41 is suitable for Earphones with a catheter diameter (widest) of 4.4-5.8 mm.
The T41 is suitable for Earphones that use a single dynamic unit such as KXXS/Spaceship/Starfield/MiRai