About: http://webisa.webdatacommons.org/404072708

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	As to the stopper, it may be a compound or multicomponent formulation based on an elastomer, such as poly (isobutylene) or ???butyl rubber??? and must be impermeable to the gas used.
http://www.w3.org/ns/prov#wasQuotedFrom	google.ca