be useful, serve / be valid, be usable (e.g. a coupon at a cash register)

protection from dust

desert (barren area)

unworrying, safe

relief / lack of worry, peace of mind / (Buddhism) equanimity

to have one's heart at ease, to feel easy, to be relieved

a function

function (as something), work

camera / video camera / movie camera / surveillance camera

attach itself to, stick, stick to, adhere, adhere to; be connected with / come in contact with, touch, reach / be attached to, belong to, join, associate with; take up the cause of