Core Diameter:
- Measure the IEM's nozzle diameter in mm
Core Length:
- Measure the IEM's nozzle length in mm
**Measuring tip**
- Using a caliper may yield the most accurate measurements
Measure your IEM nozzle. If the nozzle diameter is 3mm, select 2.7mm Core Diameter. If the nozzle diameter is 4mm, select 3.7mm Core Diameter. If the nozzle diameter is 5mm, select 4.7mm Core Diameter. If the nozzle diameter is 6mm, select 5.7mm Core Diameter. If the nozzle diameter is 7mm, select 6.7mm Core Diameter. Nozzle length is same as Core Length.