In a nutshell
Sennheiser CX 300 or Sennheiser IE 4 (or other brands) are light and small in-ear headphones provided with different ear adapters for perfect adaptation all in a small convinient protection pocket. They perfectly adapt monitoring systems like Sennheisers IEM or Lectrosonics IFB.
Earbuds like Sennheiser MX 270 (or similar) are also available.
Earbuds like Sennheiser MX 270 (or similar) are also available.