bèi yòng èr jí tóu hū xī qì
(scuba diving) backup regulator; octopus
备
bèi
(bound form) to prepare; to equip
用
yòng
to use; to make use of; to employ
二
èr
two
级
jí
level
头
tóu
head
呼
hū
variant of 呼[hu1]
吸
xī
to breathe
器
qì
device