About: http://webisa.webdatacommons.org/360472197

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	According to a preferred embodiment, the stopper is made of a substantially rigid material, such as rubber or plastic.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com