About: http://webisa.webdatacommons.org/13701850

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	The four triangular elements 62, 64, 66 and 68 are typically made of glass, although other lens materials such as plastics may also be used.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com