Replace worn and aged air suspension springs that are no longer reliable with simple, worry - free metal coil springs. (carid.com)
It worked then basically the same way it works now: a base pad with a big ol' metal coil would wirelessly send power to another coil on the inside of a phone. (theverge.com)
The Flame Refluxer consists of metal coils attached to a blanket made from copper wool sandwiched between two layers of copper mesh. (sciencedaily.com)