About: http://webisa.webdatacommons.org/423224515

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	This is extremely difficult as underreamers are required to ream and remove hard rock material and typically comprise hard, resilient materials such as Tungsten Carbide or steel.
http://www.w3.org/ns/prov#wasQuotedFrom	google.fr