What am I?

Cover the clues so you can only see number one. How many clues do you need before you know the answer?

1. I am about 10cm long
2. I am useful when a breeze sweeps through
3. I am made of brass
4. My jaws open and close with a steel spring
5. I am still useful even though it is the computer age
6. I sit still and keep my mouth closed most of the time to do my job.

Answer in next week's TreasureLink.