<http://webisa.webdatacommons.org/prov/282702615>	<http://www.w3.org/ns/prov#wasDerivedFrom>	<http://webisa.webdatacommons.org/171568428> .
<http://webisa.webdatacommons.org/171568428>	<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>	<http://www.w3.org/ns/prov#Entity> .
<http://webisa.webdatacommons.org/171568428>	<http://www.w3.org/ns/prov#wasQuotedFrom>	<freepatentsonline.com> .
<http://webisa.webdatacommons.org/171568428>	<http://www.w3.org/ns/prov#value>	"The duct walls 17a and 17b are also made of pressboard or other suitable insulating material." .