A number of similar devices have been developed since then.
Only in the 14th century did people have the knowledge to build similar devices.
Other companies are expected to follow in the next few weeks and months with similar devices.
Technology makes it possible to do these same things using a computer or any other similar device.
Other companies make similar devices, and perhaps 15,000 to 20,000 are on the streets, he said.
Successful use of similar devices was described a few years later.
He said a similar device was available in stores, for about $50.
Only a handful of companies make similar devices, he said.
Nor can they prove that a similar device was used.
Similar devices had been made earlier, but Anderson's was the first to be effective.
