About: http://webisa.webdatacommons.org/421533382

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	It may alternatively be made of a material which is less costly such as mild steel coated with a secondary emission material: a coating of an alloy of oxidized copper-beryllium or a coating of manganese oxide.
http://www.w3.org/ns/prov#wasQuotedFrom	google.ca