With the built-in Eartube earpiece you have two in-ear attachments available. The ear can be completely blocked (with the mushroom bud) or you can hear your surroundings (with the open ear insert).
https://earhugger.com/product/mushroom-bud/clear-mushroom-bud-ear-inserts-5-pack/
https://earhugger.com/product/open-ear-insert/open-ear-insert-medium-left-2-pack/
We include both with the headset.