Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earspeakers, earphones or, colloquially, cans. Circumaural and supra-aural headphones use a band over the top of the head to hold the speakers in place. The other type, known as earbuds or earpieces consist of individual units that plug into the user's ear canal. In the context of telecommunication, a headset is a combination of headphone and microphone.
Osmium is usually sold as a minimum 99.9% pure powder. Like other precious metals, it is measured by troy weight and by grams. Its price in 2012 was about $400 per troy ounce (or about $13,000 per kilogram), depending on the quantity and its supplier.
Sterling Silver Price. The current price of Sterling Silver (anything) is $13.33 per Ounce (oz), or $0.47 Per Gram (g). Sterling silver is defined as 92.5% pure silver and is widely used in high end cutlery, jewelry, and pitchers. The other 7.5% is usually made of some other metal like copper.