About: http://webisa.webdatacommons.org/233506588

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	They are available in various low densities and in various metals, including nickel and copper, but similar materials made from aluminum, iron, stainless steel, silver and other conductive metals may also be used.
http://www.w3.org/ns/prov#wasQuotedFrom	google.de